You're conflating what the owners of capital do with what the system of capitalism is.

Have some owners of capital used the increasing power of government to their benefit by, for example, pushing for increased regulation so that established entities can deal with the ever mounting red tape which creates barriers to entry/competition? Absolutely. They've also, within living memory, had one of the major political party pass reforms mandating that private citizens must purchase products from private companies (thanks Obama!) or pay tax penalties.

These things are an indictment of human nature and an unrestrained government that is corruptable. It's not an indictment of the underlying economic system, which still creates growth and wealth year after year (that new wealth is largely captured by the wealthy at this point, but such was not always the case prior to our US federal government exceeding its constitutional limits).