I imagine this comes with a ton of strings attached, written or unwritten. This probably gives Microsoft control of the project's roadmap.
TLDR either the public is being conned or Microsoft is. And assuming that Microsoft probably has used top lawyers to close the deal, I doubt it's them.
a cap of 100x on returns and limited voting power certainly changes the price investors are willing to pay for the shares, but doesn't invalidate anything or render shares worthless or anything of the sort.
a) no cap on the returns
b) give you control over the company
c) limited ability to sue if the company acts against shareholder interests
d) no due date
Differences a, b and c seem to be gone here. Would you give someone a loan where you have no ability to sue them if they never give you the money back? I wouldn't unless that person is very important to me or the money is insignificant. Neither is the case here.