It's tricky, I do agree.

In my case, I started thinking if I want to take blacksmith, armorer, or carpenter more seriously, I would need to be able to have miner and botanist at levels where I can gather the materials myself.

I have a lot more copper ore, iron ore, and alumen than I anticipated trying to level up (since most of blacksmith/armorer/carpenter levels are from mob drops, a super affordable stack of logs that someone put up once, and local leves). I imagine that once I move on from the current grade of gathering and using it, would try to sell the excess amounts.

Although for me, this would be after I make a stack of 99 ingots, plates, and/or rivets. And even then, after clearing out all outdated materials that can no longer be crafted with first (I may never sell it at my current rate).