We should differentiate two matters here.

1. are your finances going to be screwed from overpaying for SpaceX IPO shares through your index fund? No because as you say, it's a small fraction of typical index funds.

2. Is this a form of financial malfeasance? I think yes. The average 401k has about $150k in it. Even if just 0.5% goes to SpaceX, that's $750 per American. That's a few hundred billion. It's serious cash. If that's going to overpaying Elon 3x or whatever it is for these shares, that's a travesty. Even if for each individual it's a tiny blip that doesn't show up in the annual ROI graphs, it's a form of corruption. Like the programmer infamous Salami slicing stories at banks.

If the SpaceX IPO is wildly overpriced, even if you have just 300k in your account, yo