I think the amount of gold you accumulate should be how many experience points you have. And when you reach milestones you're allowed to level up.
But any money you spend keeps you further away from your next level milestone. So you can save your gold to get to your next level or spend portions of it on things like magic weapons that will be useful in combat.
That's how it used to work a long time ago, back in the days of Advanced Dungeons and Dragons. Good times.
I don't really care whether or not they add silver and copper, it's fine either way for me...but please not that 😶
I don't thing that would be fun at all.
Also...I prefer thinking that leveling up comes with achievements/merits (ie: discovering new things, winning a fight or successfully avoiding one using wits), not wealth growth.
