I think your equating hopping with age is misplaced. Yes, younger do hop more, there are plenty more senior people that maybe want something new and interesting - making it less about making more $$
I'm pointing out that as an employer (not in a startup), I'm not that excited about hiring a hopper. We tend to want folk to hang around since we invest a lot of time and effort in their training, domain knowledge etc. Knowing that someone will move on in a couple years just isn't appealing to me.
I would never hire a hopper willingly and I don’t quite know why some companies do. If I see a bunch of short arrangements on LinkedIn, then it goes on the ‘no’ pile. With the current market here, I have some hoppers begging to try them as ‘they promise they won’t hop’, but I have no way to enforce that; no one cares about options and timing bonuses and raises doesn’t work. We prefer people who stay 10+ years at a position and who don’t ’get bored’; we don’t want to be the TikTok attention span of saas; if people have that, they have to find something else.