We are seeing many blockchains become centralized, even some of the big ones like BCH, being vulnerable to 51% attacks or accept that 12.5% of the miners' profits are taken away by some unaccountable Chinese fund?
Some blockchains were not made from start to be (properly) decentralized (or not at all). Not all devs are working for a greater good (BCH and BSV are wonderful examples).
One has to read as much as possible and whenever something stinks just leave that boat.
But yes, it's a real problem and it's not new. In some cases the success of a blockchain (basically the market cap) is not reflected by the strength of the underlying blockchain (difficulty). And if this happens, especially if it lasts too long, somebody will profit by making 51% attack. Creating hype is cheap. Meeting the requirements for the success to last may be much more difficult.
About miners' profits I am not sure I understood. But wherever a businessman can find super cheap electricity, maybe also cheap miner devices, he's start a mining business there. China is such an example and I think that it's not the business men to blame, it's the idiocy (and greed) of western governments which add a ton of fees into electricity price making it unreasonably high.
But this can be beaten with enough funds and future proof thinking. One can build up on renewable energy. This will ensure on long term that one will stay in business, even after many halvings, because after ROI the energy will be almost for free (some maintenance costs remain).