A secure voting system should be as secure, or even more secure, than opening a bank account or a crypto account at an exchange. Some of the crypto exchanges are even using biometric face scanning! The slightest mistake in your application will put you in purgatory until everything is worked out to their satisfaction.
Blockchain technology has proven to solve the "double spending" problem very effectively. The Bitcoin blockchain has existed since 2009, and no one has successfully hacked the blockchain directly. It's secure. Why aren't we designing a system to issue voting tokens to each voter? Each person gets one token for each of the races they are eligible to vote in. They can go into the voting location to spend their tokens on election day, or even spend them on a secure banking style app on their phone from home.
Another method would require only in person voting, with paper ballots, and a blockchain backup to detect errors and provide an early indication of results. The results would not be certified completely until both the blockchain and the paper ballots were properly counted and verified.
Why is this so hard?
One answer for why it is so hard is that the deep state would not allow such a system to exist. The people designing it would probably die in car accidents at a rate that's unbelievable. Truly secure elections with no chance of cheating would finally and completely return power to the electorate. It would mean the end of corruption forever.
Not going to happen in NC - Roy Cooper was fraudulently elected and we use ES&S. machines. I became a poll worker to see what was happening and got nothing from my precinct captain but happy talk about the machines. No way to check what comes out of them. We ran the ticket at the end and no one suggested that there might be another way to check the vote. Cooper is in bed with the CCP(check his history and the company he keeps) and my frequent calls/emails to both Cooper and the NCBOE have been ignored. Don't move here. The state is awash in corruption. Lots of nice people but TONS of liberals who love LGBTQAI and not the country. My neighbors (with whom I try to get along) fly a large LGB etc. flag from their porch and have a Don't Tread on Me (with vagina picture) in their front yard.