Because they can't allow an alternative to the current system to flourish. An outflow of cash form existing banks to a new alternative will evaporate the possibility governments and central banks have to print money, redistribute wealth and thus control power. Blockchain is a very amiable initiative, but being nice doesn't prevent any flourishing innovation from being dragged back in and drown by it's spiteful competitors. And no, they shouldn't be doing that, from a moral point of view. More and more viewers on my channel are from abroad, so more content in other languages besides Dutch will be published. Please watch my contribution to the matter at hand at the september 2018 BitCoin Wednesday meeting. If you like my work, please consider supporting me on BackMe.org.