Very true because HODL instead of mining is really much more profitable compared to mining.
Mining is a really professional business and maybe some of your have viewed the graph, where the mining difficulty has been visualized. Mining difficulty is going up much more than Bitcon's price because mining is really a competitive business.

Good point and aside from the fact that mining is a business done by professionals, not average Hodlers who don't have any experience in Computer Technology, your miners get old pretty quickly because new miners are developed by Bitmain and Co. frequently.
So, your shares of the total hashrate go down every time your competitor miners are getting more modern (and powerful), you'll lose shares of percentage of the total hashrate. 

And good point where you've said every time it needs to be checked, we need to hire or call a computer specialist to set it up and whenever a problem arises, we need to call him... It's very annoying because it's also a consideration for our profit evaluation, where we lose time once our called computer expert will liik into it. Aside from extra costs, which your mentioned correctly.