One issue with capitalism — and every alternative system would have its own variant of this problem — is rent seeking. Players become so powerful within the economic system that they no longer play by the rules, but rather write the rules to their benefit. This allows them to extract value instead of creating value.

This is a run-away positive feedback loop which is kept in check by regular revolt and redistribution of wealth (see eg. the labor movement).

Yes. The obvious solution is to either design your politico-economic system that big players never emerge, or are such that they don't have incentives to corrupt (eg. SOE).

Another example of the latter, is that large companies should always be majority owned by their employees in a 1/N fashion. The idea being that even if such players try to rent-seek, at least the rent is being extracted in favor of normal people rather than a small class of rich people.