So, I thought Seasons was the solve to this. So many of the levels are Gold, or Doubloons, or Ancient Coins (real money), or Cosmetics (the main thing we spend these things on). If you are playing 4 hours and not making at least some levels that is a special skill I don't understand since you move up levels just playing the game (heck, even just sailing distance will raise this). If you have your Season maxed out, that is just the way of it. At least, even if you didn't sell a single bit of Loot all Season you still made every single coin on offer from it as well as some new cosmetics, and hopefully made some headway on some Commendations and Milestones and Achievements.
Over that session, you probably still made a couple grand in coin from Seasons - exactly what you are trying to save. So, what is the difference other than walking a piece of loot to a vendor and clicking a button. You've still earned some coin, made some progress, maybe even ticked off a Milestone or Commendation or Achievement.
If your only definition of having a good time is to hand in a Chest, Skull, Crate, Animal, etc and see the coins go up then that is going to be rough cause you absolutely will lose Loot in this game. PvP is always a risk, sure you might get rolled easily but the crew coming in doesn't know that. There are solo sloops who can take on Galleons regularly, and the same applies through all the categories. Sometimes they find an easy kill, sometimes they spend lots of time hunting only to get rolled themselves.
Every approach has risk and reward to it as everything is intentionally connected in various ways. So you don't need to keep your Loot if you lose an Encounter (just like if the Kraken, Skelly Ship, or Meg happens to take you out - cause yes, this can happen even if experience makes it rare, but the same applies to PvP in that experience makes you better and thus makes losses more rare).