It takes more than majority vote to add a new amendment.
Go ahead and try, but I don't think you'll find that an amendment to restrict people's freedoms is going to be very popular. Because it will be seen as anti-democratic.
I'm not following you. I didn't say 60%? And 60% is a supermajority, not a majority. Which is a huge distinction. And US constitutional amendments require much stricter thresholds than that -- two thirds of Congress and three quarters of states. That's a gigantic bar.
Yes voters try to restrict their own freedoms all the time. We have constitutions with rights to block them from doing that in fundamental ways. That's what protection from tyranny of the majority is all about. Just because you have a majority doesn't mean you're allowed to take away rights. That's a fundamental principle of democracy. Democracy isn't just majority rule -- it's the protection of rights as well.
And no, that would be the courts at work, which may or may not be beholden to the whims of other political figures.