Endless supplies of materials/resource on the field is an issue. Supplies need to adjust depending on population.

One way of doing that is a change in the re-spawn mechanics. If for example an ore field has taken 2-3 weeks or more to respawn (or in other words to mine-out) then next spawn field will have half the supply on next respawn and so on. If it has been mined in a day or two, then the next respawn will increase supply( bigger field).

I know this does not solve the issue right away, but endless supplies of stuff is still an issue, cooldowns for re-spawns where devs can control the amount of resources 'against time' entering the game so it does not, break the delicate supply and demand.