If you'd asked me 25 years ago, I would have said no. And ironically, I smoked weed back then. But because I had experience with it, and with seeing what the habit did to some of my friends, I thought it would be an overall negative on society. What did it do to my friends, you ask? It made them irresponsible wrt: school, job responsibilities. They partied till late night/early morning, then would oversleep and miss class or show up late to work. Get fired. Get bad grades. It's like turning the volume knob down on potential. I saw some who exercised self-discipline, and one person in particular kept me somewhat on the rails then. My roommate my junior year of college was a guy who had flunked out when he was 19, then went in the Army. Made sergeant in 5 years, then came back to school. He refused to go out drinking or smoke on school nights. He got blasted every Friday and Saturday night. I mean drunk, stoned, even coke which I didn't do. But on Sunday night, it was coffee and books again. He graduated Summa Cum Laude. Being about 7 years older was a big part of it too, but his insistence on "showing up right" was the real thing that made him succeed. Most potheads I've known though ... they just will not turn down a bong hit.
But now, I'm in favor of legalization, in spite of the "couch" effect. Why? Because the negative impact on society that comes from trying to prohibit it is worse than the decreased outcomes that most people who smoke weed will 'suffer.' Keeping marijuana illegal empowers and enriches scumbags on the dealer side, and nurtures a totalitarian tendency on the law enforcement / govt side. The "war on drugs" has resulted in damage to our liberty (decades of Court decisions narrowing the 4th amendment), created the militarization trend for police and sown public disdain for the law generally, and created a gang culture in inner cities which young people who grow up there must be a part of by default. Not to mention the lives lost and violence from the criminal black market activity that prohibition necessitates. All of this has had a far worse effect on us than some people being lazy stoners.
Legalize it. But when you smoke, stay home, walk, get an Uber. Just don't drive. (don't even start with "I drive better high." That's bullshit.)