That's just the way the world is, surely. In my field there are early career actors, musicians, dancers, producers, designers, directors...all in the same position. The hours are long, the work's hard, the annual pay often doesn't even add up to minimum wage, and the training is among the longest of any career.
Do people advise youngsters against it? Definitely. Is there a shortage of entrants? Nope.
They have ambitions, they know they've the potential to be good at it and would be frustrated doing something else. The fact that it's such a hard choice is a really effective way of weeding out the not-very-committed and the not-very-good.
I will say as a small counterpoint that I am sure there will be good young researchers who are dissuaded by these arguments, as I was dissuaded from pursuing a career in music when I was young. Not that aspiring researchers (or musicians) should be shielded from the financial truth of things. But if there is not also someone to tell them what the good things they will gain if they choose to risk it, they may balk at the warnings and end up making a compromise in terms of their career.