In other words, if I had a 40k right now, should I buy a model such as the Antminer L7, for instance? Purchase a single bitcoin, if that is your preference.
1. Mining requires a lot of electrical power and in my country, power is a really big issue right now.
2. It doesn't end in buying the mining, you still have to set it up, which requires a lot of time, and you might end up hiring someone(extra spending) to do the set up for you if you are not learned enough.
3. Miners can develop issues as time goes by, you have to hire an engineer who can fix it if at all, there any, and in my country, I don't know neither have I heard of anyone with knowledge of how to fix faulty bitcoin miners.
4. Mining machines require maximum security to protect it from being stolen, and this means you have to give it serious attention.
5. Mining machines are built to run 24/7, this is the only way you can have opportunity of earning decently, this can really be frustrating in a city or country with epileptic power supply, except you have your own power source that's guarantees you 24/7 power supply.
This are the few I can think of right now, so to be sincere, for me personally, the stress involved in buying a miner to mine your own bitcoin is just way too much, it's not worth, so I prefer to buy my bitcoin from the open market.