In whose reality? He's been the best pitcher in baseball by various measures over the last few years. He got market rate based on the pitchers most like him. And if they'd given him $30 million it would have been a five-year deal. Offer 25-28, he's playing on this same deal for another team next year. And the Phillies did have to overpay based on how much he outperformed the current deal.
Yeah, he's older but signing any pitcher - Snell, Burnes - comes with risk. And they'd all have longer terms (ultimately), while few of them (Nola included) are as good.
This is the path they've chosen, and there's really no better one now that they are on it. If it all falls apart they will have to rebuild, or carry $325 million in salary (and there's no reason they can't do that unless the Bucks and the third owner aren't on board. But that doesn't seem to be the case. The purpose of the third owner seems to be to make it easier to spend, even).
If a few holes do pop up over the next two years you fill them with youth or mid-level free agents, not stars. After that, god willing, you fill them with more youth.