People who work on their own startups on evenings and weekends aren't generally considered to be taking a very large risk. People who'd do contracting for equity in other startups where there is already some traction likely less so since there is more likelihood of those startups being successful.

Also your post implies you are looking to do this for multiple startups. Not only does this kind of send a bad message that you'd not be that invested in a company you literally owned, but it also reduces your risk profile since you are trying to "diversify."