You mean like putting a lot of money into opposing legalization efforts? Yeah, I expect that.

Wouldn't they be more likely to just enter the market as legal participants? Cartels kill and do heinous things to their competitors because they can't take them to court and sue them and get an injunction to stop bad behavior.

That's not what happened with Prohibition. Crime syndicates providing black-market alcohol didn't just set up as legitimate alcohol vendors, they moved into unrelated markets like controlling labor unions.

Note that labor unions were a legitimate type of enterprise, but organized crime ran them illegitimately anyway. The willingness to break the law is their competitive advantage; it would make no sense to give it up.

Agreed this is too simple and common sense for the government to do.