It appears (good statistics are hard to come by) that these two facts are simultaneously true:

  • Most students who enter a PhD want to go on to have a career in academia (researchers, professors, etc).
  • Most students who enter, or finish, a PhD will not end up having such a career.

It also appears that, as those who do succeed (professors, etc) are not in the sample set of those who “failed”, they generally do not perceive (may not even be aware of) this problem (they became professors so surely others can too), and do not much to disabuse PhD students of this belief/desire that is far from reality. If true, this is a problem. It would be much better for everyone involved if students entered a PhD programme with realistic expectations, and if in the course of it they were prepared for a plausible set of future careers.

Here is an article about the situation in the UK (focusing on arts and humanities PhDs, but I think the situation may not be very different in scientific fields):

Is pursuing an academic career a form of “cruel optimism”?

I think the situation may not be very different in the US.

I got into a discussion online about the situation in Europe, Spain in particular, and tried to find some statistics. Collecting some related references I found with a quick search:

  • “Factors determining the career success of doctorate holders: evidence from the Spanish case” by J.F. Canal-Domínguez & Alan Wall: https://doi.org/10.1080/03075079.2013.806464

    Mangematin, Mandran, and Crozet (2000), using French data, notice the difficulties PhD holders who graduated after 1995 had in finding employment. These authors highlight the importance of the training period – in terms of whether it is oriented towards scientific publications or towards transfers of knowledge to the private sector – for the professional future of PhD holders, given the differences observed between universities and industry with regard to salaries, job stability, promotion and so on as well as the difficulties of moving between these sectors.

    Several descriptive studies exist which analyse the professional trajectory of PhD holders. Some recent studies of this type include Schwabe (2011) for Austria, Raddon and Sung (2009) for the UK, and Auriol (2010) for 27 OECD countries within the framework of the Careers of Doctorate Holders (CDH) project. For Spain, few studies exist due to the unavailability until recently of data. Canal and Muñiz (2012), using the same database as the present study, analyse the factors determining PhD holders’ choices of professional career. They found that the destinations of PhD holders have been undergoing a notable change, with private and public companies rather than the universities now absorbing the majority. The driving force behind this change was the higher expected salaries compared to those in the universities.

    The database used is the 2006 Survey on Human Resources in Science and Technology, representing an exhaustive study of PhD graduates under the age of 70 who are resident in Spain and who obtained their doctorate between 1990 and 2006 from a public or private Spanish university. The total number of selected individuals was 17,000. The response rate was 74.5%, yielding a final total sample population of 12,625. The reference period was 2006, although some questions referred to the month of January 2007.

    The respondents are divided into areas of knowledge, three of which were very prominent: natural sciences (29.2%), medical sciences (22.6%) and social sciences (20.8%). These three account for almost 73% of the respondents. Some way behind are humanities (14%), engineering and technology (9.6%), and agriculture science (4%). Science areas therefore predominate. With regard to the sectors where the respondents work, 45% belonged to higher education institutions, 36% to the public sector, 14.8% to private firms, and the rest to non-profit institutions (NPIs). The fact that more than half of PhD graduates do not work for teaching institutions reflects…

    The rest of the paper has a lot about “success” and job satisfaction, for men and women, etc.

  • (The “Canal and Muñiz (2012)” referred to above.) “Professional doctorates and the careers: present and future. The Spanish case” by Juan Francisco Canal Domínguez and Manuel Antonio Muñiz Pérez. https://doi.org/10.1111/j.1465-3435.2011.01514.x

    Why do people embark on doctoral studies? What returns do they expect?

    As the rest of Europe also lacks information, the EU backed surveys on this cycle by passing Regulation 753/2004 on science and technology which defines the framework to generate statistics about PhD graduate workers. The National Statistics Institute (INE) carried out the ‘2006 Survey on Human Resources in Science andTechnology’ in 2008, which was an exhaustive study on doctors who obtained their degree between 1990 and 2006 at any Spanish university.This article outlines their characteristics.

    Similar statistics, something like 44 to 49 percent of PhDs are working in universities. Among science PhDs it seems to be about 37%, and about 60% among humanities and social sciences PhDs, as one can infer from the (many) tables.

  • “The employment of PhDs in firms: trajectories, mobility and innovation” by Laura Cruz-Castro and Luis Sanz-Menéndez (2005) https://doi.org/10.3152/147154405781776292 (A draft(?) version seems to be here.)

    to tackle two sets of general questions. The first relates to the incentives for doctorate holders to pursue a company career versus an academic career. The second concerns the flexibility and/or reversibility of career options for young PhDs and the relative value of a doctorate outside academia.

    Although the majority of them had a preference for the public research sector during their doctorate (54.9%), preferences were quite balanced. In the areas of research represented in our sample, still 45.1% of PhD students had preferred a job in the private sector after their doctorate, while doing their PhDs. However, the expectations about future employment prospects were negative in the 69.8% of the cases, especially among those who preferred a job in the public research sector, among which more than 80% thought that there were few possibilities in this sector for their research area, as compared to a proportion of 56% of pessimists among those who preferred the private sector

Probably less related: