Is employee co-invest overrated as a compensation sweetener?

I’m trying to sanity-check how people think about employee co-invest as part of total comp, particularly at family offices and smaller PE platforms.

On paper, co-invest is often positioned as the trade-off for lower cash pay. In practice, though, I’m struggling to see when that trade-off is positive for junior/mid-level professionals.

What I keep coming back to is illiquidity versus median outcomes. Even assuming gross, no-fee/no-carry economics, median company-level outcomes don’t obviously outperform simply putting the same dollars into a liquid  index fund over the same time period. Also, with levered co-invest if the structure isn't a non-recourse and repayment from deal proceeds only it really just seems like personal leverage you're taking on.

Also, beyond the pure math I’m interested in the soft factors when co-invest is described as “optional” is it truly optional in practice? Do people feel real or perceived pressure to participate to signal alignment or commitment, and does opting out actually carry any career cost? 

I’m not anti-co-invest and I understand the potential for outsized winners but I’m curious how many people believe it’s genuinely a sweetener early-career versus something that only makes sense selectively or later on.

Would appreciate perspectives from anyone who’s actually lived through multiple cycles and exits.