It could still protect you from one or more strains that you haven’t been exposed to through sexual partners and avoid contracting or passing it along to a future partner. There’s no practical way for a man to be tested for HPV (I asked and the doc said “it’ll be very painful and the result will be the same: get the vax”)

I experienced zero side effects when I got HPV vaxxed at 38yo.

There some circumstantial evidence it could help with plantar warts, too.