I see a lot of misconceptions about weed here. As recreational smoker, I know a lot of people who use it. For most of them, it's an occasional indulgence, the same way most people use alcohol to relax after a long day, hang out with friends in an altered mindset, or make ordinary situations more fun. Most people go through periods where they smoke a lot, and gradually adult responsibilities take over and they use it less or stop completely. Some people use it problematically, it impacts their ability to do other things they should be doing, they experience adverse mental effects, or they smoke so much they fail out of school or can't find a job to support themselves. I know one person who has schizophrenia and also smokes a lot (plus alcohol, tobacco, and other drugs) but I don't think it's possible to definitively determine that he became schizophrenic because he smoked pot, there are way too many other factors.
I do believe that now that it's legalized, there will be better research, the ability to know exactly what you are buying, more availability of specialized products like concentrates and more recognition that it is not some scary dangerous substance that leads to disastrous circumstances for everyone who uses it.
Tobacco and alcohol are addictive, and legal. Most people who use them aren't degenerates, and neither are most people who smoke weed. Legalization brings it out in the open, and there will be some social changes, but I think it's going to be mostly positive. The people who are most at risk and need help managing their addictions can get help without the same kind of stigma. I personally believe that we'd all be better off if all drugs were legal and sold with quality controls, taxes, and stigma-free resources available for users, but I doubt that will ever happen on a large scale. Until then, it seems like a lot of money and resources will be wasted on criminalizing people who mostly just need help, and don't pose a danger to anyone but themselves.