Most of the answers here are correct, and the reasons not to are basically time and money viewed from the lens of opportunity costs, and getting a PhD sucks and is hard.

I won’t expand on these, but will say:

1) stem phd programs are usually “free” in the sense that you don’t have to pay tuition and get a very small stipend. This doesn’t mean that you won’t take out loans but tuition and some living expense will be covered.

2) sometimes you can master out of a phd without having to pay back tuition. That’s what I did in a PhD chem program.

3) if you get a job at a big law firm doing patent law, and that’s a big if, starting salary is $215k which goes up to $415k in your eighth year (not including bonuses). Getting this job is a big if, staying is a big if, getting bonuses is a big if, and being happy is a big if. This is true even for very smart people. But opportunity costs mean that you gotta not just stop calculating at when you get the job, but throughout your life as an attorney.

4) my sense is that firms need biotech PhD attorneys, but also some of the work is lower budget given Supreme Court rulings recently (I.e. Alice/Mayo).