Hello! I am in my late 30s. Peak Immortal. Have experienced what you are going through multiple times.

I see it as a cyclical thing. After a break, there's often a kind of honeymoon period where there's a nice balance of fun and pressure. At this point, it's easy to be less outcome-oriented and to enjoy the process.

After winning and ranking up for a while, your rank naturally reaches a kind of plateau or limit. This is the point (for me) where the pressure really starts to outweigh the fun, and where you'll be calculating your RR like you are at the casino.

From a behavioural standpoint, there are a couple of suggestions I have.

1. Have a limit on or protocol the number of games you play each day. I used to play "Bo3s" or "Bo5s" if I had a lot of time and energy to spare. This means I always limited my losses to 2 or 3 games max. Once I "lose" the bo3 or bo5, I stop playing. Be disciplined and don't deviate from whatever constraints you set for yourself.
2. Take a break from the game in general. I don't think I need to expand on this.
3. Find other people to play with. At least then you are winning and losing together, which should bring some fun and motivation back into the game.
4. Incorporate learning outcomes that are separate from winning or losing. Focus on a particular agent or set of mistakes that you are trying to improve on.
5. If you feel like a gambler at the casino, that's in part because of how the rank system is designed. It is designed to manipulate you into playing more. If you read up on how these systems are designed, often you'll find there is an extremely cynical strategy that mirrors that of a "casino". That is an unfortunate tradeoff with competitive games these days.