>You get to meet interesting people.
I want to stress that part because I don't feel it does the environment justice. You get to meet fantastic and very intelligent people from all countries in the world. During gathering events, meetings, parties, etc. I've been to, it's not rare to see eight different nationalities out of eight people around a dining table. You talk about science at first but very quickly discussions derail into comparisons between such and such country's perspective, differences in culture, jokes about the language, and so on. And it happens every time. Not all environments provide this.
Of course, you may argue that this diversity of culture and insights is counterbalanced by the community's homogeneity in many other aspects (e.g. the overwhelming majority of scientists are very liberal, even by European standards), and it's pretty obvious that your view of, say, Iranian or Russian people is going to be skewed if the only ones you've talked to are very educated and liberal 20- or 30-somethings working as expats. Scientists are known for their insularity, and while they're a demographic that's among the most susceptible to date outside their country, they're also very prone to date inside the community. The 'ivory tower' stereotype is not completely wrong.
But you did it and you did it with the "it's pretty obvious" qualifier.
This casual bias needs to be corrected.
One of the main points brought up here and elsewhere is that getting a tenure-track position is hard: you're basically in a giant tournament. And that tournament continues to actually get tenure. So I don't disagree with you, but you're starting from the assumption that one has tenure, which is very much not a given for the vast majority of grad students.
(Yes, yes, I'm aware this is not strictly true and that many lottery winners end up declaring bankruptcy and often report being miserable. But it works as an illustration.)
There are many things to consider. How bright you are, what is your research topic and will it be popular in a few years, who is your PhD advisor, are you willing to work abroad and so on...
But I agree that there is uncertainty for most people and graduate students should have an exit plan, e.g. keep their research or teaching work relevant to the job market.
My (European) experience is that academia provides a great work environment. If you have tenure, you're free to work on whatever you want, you have very low pressure (beside the pressure you decide to inflict on yourself), you're basically paid to learn new things and teach them to others. You can easily visit other institutes abroad. You get to meet interesting people. Age discrimination isn't an issue. The salary isn't on par with what you could make working for a company but it's enough. If you're ambitious and talented you can easily earn money on the side (consulting, starting your own company, taking a leave) and you can have the best of both worlds.