Since there is no IQ test for voter registration, opposition to compulsory voting does not in any way, shape or form address that problem.
Nor are people "stupid" because they choose not to vote. Rather, the US makes it difficult to vote. In most states, you have to register in advance; there is no single central clearinghouse to coordinate registration, and each jurisdiction handles it slightly differently; polling stations are often crowded; polling machines can be difficult to operate; and of course, Americans don't get time off to vote.
And of course, there are overt attempts to suppress voters, by proclaiming fraud where it doesn't exist; instantiating voter ID laws, and then making it difficult to get IDs; targeting minorities with "surgical precision" with voter restrictions and closures of polling stations; and gerrymandering districts in the attempt to nullify the impact of votes in the first place.
Even if you don't think that compulsory voting is a good idea, the idea that "the fewer people that vote, the better" is arrogantly and unjustifiably anti-democratic; a sad indicator the contemporary conservative point of view; and a cynical response to the lack of popularity for their policies.
More irrelevant nonsense.
Almost 40% of the prison population is unnecessarily incarcerated. Around 25% are low-level, non-violent offenders. Another 14% are elderly and have basically aged out of criminal behavior.
How Many Americans Are Unnecessarily Incarcerated? | Brennan Center for Justice
We should also note that, for example, less than 4% of federal prisoners are there for homicide, aggravated Assault,
and kidnapping combined. Around 45% are there just on drug charges.
Plus, compulsory voting doesn't automatically include prisoners. E.g in Australia, if your sentence is 3 years or longer, you can't vote while you are in prison.
Even more factless nonsense.
1) Crime rates have fallen in the US since 1991. How do you not know that?
2) There is no correlation between crime rates and incarceration rates. E.g. the US has the highest incarceration rate in the world (655 per 100k), and has a crime rate 4 times higher than nations like France (256 per 100k), the UK (140 per 100k), Denmark (63 per 100k), Japan (41 per 100k) etc
So no, locking up people for the sake of locking up people does not in fact reduce crime rates. What it does is fatten the bottom line of for-profit prisons, disenfranchises people (almost all poor and minorities, what a shock), and perpetuates a variety of racial injustices. That's not a great way to fix the US.