on this situation probably mining is more profitable than investing in bitcoin, but when it comes mining it's too expensive because like what you said before you can build miner you need to complete first those requirements in order to mine bitcoin..unlike investment wherein effortless.  Infact if your plan is for long term then perhaps it's still a good idea to invest than to build miner because it's too expensive and for sure there's no big difference when it comes profits that you will earn on it after all.