I'm also 30 with a masters in science and a 9-10 hour day job. There's no such a thing as too old to play this game. I get mad sometimes as well, especially because I play jungle. That's why you use the mute button. Just understand that a lot of times people are not actually hostile, they're just making salty comments (sometimes as jokes) because they're frustrated. But when you're on tilt you tend to treat them as hostile comments.

High elo isn't necessarily better, if anything, you'll get called out for being boosted if you don't perform to the expected level.

3:1 KDA isn't bad, but judging from your op.gg it definitely looks like your understanding of the game isn't very good. Your average kill participation for the last 20 games is 42%, that's actually extremely low. There are a lot of master/challenger smurfs in low diamonds and they tend to have 70%+ kill participation because they're hard carrying games. It's even worse because you said "you tried to help everyone." If I have to guess this probably means that you're responding to teammates that are asking for help, but you're not necessarily helping them.

In order to actually help your team, you need to make decisions for yourself but not just gank the lane that's spamming pings or being toxic. The single biggest frustration I have when I play in normals with silver players is that they don't seem to understand this is a team game. If your teammates gets caught in the river, you don't just call them out while farming in your lane. You need to actually go there and help them, because that's how you carry games. Champions and roles are of less importance as long as you have a good understanding of the game. Knowing and more importantly, predicting when and where you need to be is extremely crucial in this game.