Sounds horrible tbh. A big part of the hobby is meeting new friends. This sounds like a good way to become socially isolated and depressed.

In my personal experience that’s much more difficult

If this happens, the RPG is too complex for that player. Play a simpler system.

B/X is good. When characters have d6 hp and it’s instant death at 0 the combat becomes way more serious and tense.

If you’re going to die, better to die on the main quest. I avoid side quest distractions.

The best lore is lore made at the table with the players. The rest is just gm inspiration.

If you’re running a sandbox, you just need to review a bit ahead of the party in the various dungeons.