In most programs, if you get accepted into the Ph.D. program, you're funded. Obviously, you should check first. Different programs treat these things differently with TA requirements, but most Ph.D. students are funded by an "RA" (research assistant, aka, doing your actual eventual-thesis research...).
Oh I'm funded. Definitely was told not to go unless I'm fully funded. But $500k for computing resources is bigger than a lot of small term contracts (I'm mostly on research and usually don't have to TA unless there's a hiccup in funding schedules. Gov money...). I definitely see that amount for long term, but this seems like a pretty short project.
Got it. (1) Yes, 500k is a lot, but (2) the TFRC program is making fairly expensive TPUs available at shockingly good prices for researchers willing to do some tire-kicking and feedback-providing. So 500k of TPU time is easier to come by than, say, 500k of generic compute.
For more info, my colleague Mor wrote a very useful doc about the Ph.D. process in CS: https://www.cs.cmu.edu/~harchol/gradschooltalk.pdf