maybe require a certain amount of signatures?
Now we get into questions about electronic signatures and should they count. Plus there has to be a massive infrastructure in place to prevent against fraud. If millions are on the line, I can easily envision millions of people getting the necessary signatures.
Then we all have to agree on how the money can be spent. Then there has to be a mechanism in place for auditing the expenditures. Questions about who can contribute, etc.
Maybe it can be done, but the investment, IMO, would be massive.