Comment by timeflex
And then you make it so when the tyrants do get back to 51% that they can just ignore the constitution instead. And might as well make sure there are only two major political parties so even though the tyrants ignore the constitution, that the other 49% will stay busy stuffing their pockets with foreign donations.
These are independent problems.
To prevent the government from ignoring the constitution, create remedies in each of the other branches of government. The US doesn't make this as strong as it should be. Constitutional challenges in the judiciary get shut down as a result of standing or sovereign immunity when that ought not to happen, and there should be a better mechanism for states to challenge federal constitutional violations.
The two-party system in the US is caused by first past the post voting. Use score voting instead. Not IRV, not some other nonsense, a rated voting system that removes the structural incentive to avoid spoilers by limiting the number of parties.
"The existing system isn't perfect" is why you improve it, not why you give up.