Mining in General

I have a couple questions...
Is it more profitable to invest hardware to mine coins
or invest in just buying the coins,
or selling the hardware has partial, full, and empty miners?

The price for a miner ranges depending on GPU and if you set it up yourself or buy one, but it is anywhere from 2500 to 6000. And that is just one mining rig that put up about 150 mh/s. You could easily invest that back into a altcoin and be pretty profitable right? Or could it be a better idea to just build these miners and flip them for a profit. I imagine someone could get the price of a miner down pretty good, and sell it as a complete miner to people who just want to start mining instead of spending the time building....
I dont know I am pretty new to this crypto market, but it is the future and I would love to be a part of it! Just tell me what you think or maybe what you have experienced with the market.
Thanks!
P.S.
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