This contrasts with AWS, Nvidia, GM, or AIG: it's not so easy for new comers to take market share. You gotta have a lot more going for you than a data center monthly rental bill.
Sure, you are supposedly paying them (by your tweaked rules that gives them more reward per block), but you are paying them in a currency that is incompatible with the software used by every exchange, every bank, every supermarket, and every other user, who all see your "more profitable" blocks as "invalid"... they are buying real energy and you are giving them a currency no one has heard of or accepts in exchange for goods and services.
What makes these networks hard to get everyone to switch between, even when they suck, is thereby all of the momentum of software deployment and brand recognition and "belief in the value of such" that they have. This network effect is extremely difficult to quickly replicate and is a massive barrier to entry for not just newcomers but even mere upgrades... bug fixes to these protocols require everyone to agree!
Truly: if you could just create a new network that was slightly better or which paid miners slightly more per unit (which isn't real value) and somehow immediately sweep away all of the miners, Bitcoin--which is clearly an antiquated piece of shit to most of the people who work in this space--wouldn't exist, as not only do new networks come out every day that offer small improvements but new networks exist that offer large improvements, and it is extremely painful to get anyone to switch.
At least in the case of the Bitcoin lineage, _tightening_ rules is not too hard (soft fork), while _loosening_ rules (eg. increasing supply via hard fork) is hard.
If you are the dev, control all miners and run all the nodes of your fork - everything becomes trivial (and quite useless)
To make a change to the actual behavior (such as to make new money or move money without authorization)--as opposed to merely the order of events (which is important, of course: it allows you to change which of two parties got money if someone tried to send money to both and only had enough for one)--requires the users to all buy into your new fork, not merely the miners; this is something many people seem to get wrong, but it is the most important property to understand: the rules are the rules and no one can change them without pretty extreme buy-in (which does happen, but is quite difficult to pull off).