So? How does that affect anything in the comic?
Again… so? The mean time may have decreased, but that does not mean that (a) those years don’t still suck, (b) the variance still results in a lot of students taking forever to get their doctorates, or that (c) this isn’t a symptom of other problems decreasing budgets in the humanities putting stresses on faculty and students to graduate or reject them faster!
And the specific comic you posted was meant to be funny, not characteristic.
For lots of reasons, such as concerns that a bachelors or masters won’t be adequate, or because they were accepted to grad school but not to a decent job, etc. Just because more people are doing it does not automatically mean it is a good thing. It also does not mean that they are all getting jobs for which a PhD is either a requirement or an asset.
Well, we are getting a little specific now. I am also in engineering, worked in industry and then took a detour to get my PhD (in progress). I know people going through the tenure process, and I know what salaries are still like at my company, and it is not as clear cut as you are making it. In my department, assistant profs are making about what we pay new PhD’s at my company right now, and the full professors are making almost $100k less than the top engineers (not management, engineers) at my company make. The professors have more total earning potential, because they retain at least partial intellectual property rights, but it is at best evening out.
Further, tenure is no laughing matter. I have a friend who just got tenure in engineering a couple of years ago, and for 6 years he was working himself to death (compared to the 40-45 work weeks at my company). He immediately wound up on the tenure review committee and is seeing something like 50% of the tenure-track faculty denied tenure. That’s 50% who are still working themselves to death at a new school, or abandoning academia, and he is at the #1 department for his field in the country.
We have them in my department. And yes, they are called post-docs. And while it is getting less common in engineering in favor of “research scientists*” , in other fields it is still the norm. And again, the life of the post-doc depends a lot on the field and the university - there are indeed a lot of post-docs still living like the comic suggests (I know a few!), but really I am not sure why you would consider “The Big Bang Theory” to be a realistic depiction of anything. If nothing else, Sheldon would have been medicated or pushed down an elevator shaft years ago!
FWIW, none of the characters on that show (other than those in pharma) show any sign of significant income. They share apartments, have few major expenses (2 cars between the lot?), and live fairly cheaply. Other than splurging on geek toys, I see nothing to indicate that they are making a good salary as opposed to just being frugal!
*: Research scientist/faculty is not necessarily superior to being a post-doc. The money may be better, but these positions are often permanent, with no expectation of getting a tenured position.