Maybe a bit late, but I wanted to comment on this: I think the AI boom made people forget what a PhD was meant for. Now it's going back to its original purpose: not short-term profit, but long-term research that might not have a practical use for another 10 or 20 years -> Backprop existed decades before the deep learning boom. A PhD isn't for everyone, and that's okay. Industry may suit you better if you want to build something useful now, or academia if you believe in a problem industry doesn't care about yet. The AI boom made a PhD look like preparation for an industry job, but that was never its main purpose.