so, let's use bitcoin for our example, but its the same for all the others.
Bitcoin is 100% centralized. for one, it's development is now completely controlled and in the hands of the blockstream company. But also it's network is completely in the hands of the top 3 or so mining pool. You say that many people are required to stop bitcoin, but this is false, you simply ASSUME that this is the case, but you have no facts to support it; and this is fact because we have no idea who runs the pools. The top 3 or so mining pools are operated by completely unknown entities. And since they voluntarily "split" a few years ago to prevent a 51% attack (because they had it since a long time ago), it is very safe to assume that all top pools are operated by the very same shadowy entity in the back.
If this single entity decides to stop bitcoin, at any time it wants, it is the end. NO more blocks. They can of course also block any transaction they want, because there is no accountability at all, and they select all the transactions. If this entity blocks your transactions, who will you turn to? there is no accountability, and this is the worst form of oppression.
if something like that happens, simply the 3 mining pool will get traffic shutted down from all world miners, don't worry.
and for what? for a little reward of BTC for only 1 block mined?
losses are more than the future incoming from keeping the pool active (remember that they keep a % from every block) so the money reason is itself a reason to don't create problems.
moreover the BTC reward (as any other coin), is not decided from mining pool but from the bitcoin software itself installed in billions of computers, not from your own company, fixed amount halving every X blocks, currently 6.25BTC (300k$ at current rate) anyway let's continue the calc: every day are mined around 144 block, they are about 48 for each pool statistically speaking, 48 daily blocks * 6.25 BTC = 300 daily BTC mined from a pool, 300 BTC * 1% commission (sometimes even more) = 3BTC daily incoming.
do you really think a pool will broke their work to get only 1 block (6.25 BTC, when they can keep getting 3 BTC daily only from commissions?)
even if it should happen and let's say they became crazy... simply all people will get back to solo-mining or going to a new pool, difficulty will be automatically lower and old pools will get nothing anymore. this is what DECENTRALYSED really means, that no one can control it, only if someone get 51% of mining hashrate that nowday is about no more possible considering the amount of people.
in your case it's YOU and only YOU or YOUR COMPANY to decide the amount to givem to mine, and who can get it.
this is NOT how a decentralyzed work.
who can assure us that the blocks with 180/200 IUM mined at once are not yours after you cut out other people from network? (i'm not saying you did that, but who can assure? can not be proof of that until the reward system is based on your own control and the chain can be manipulated from only 1 user)