Easier said than done, obviously. But maybe we should try to make it easier?
I can imagine a downward spiral of government regulation creating moats for companies that take advantage of the lack of competition, leading to ever more government interventions that further entrench the status quo.
Are you serious? Why would existing large companies allow this? And even if you succeed they are just going to buy up the company.
Beautiful example of this is large IT companies buying startups and stopping competition.
Wonderful! Easy money. Then you go and start another company. Keep doing that and enjoy the profits.
Your large competitor can't afford to keep buying you out forever.
Not saying this is in fact the case, but with trillions of dollars of QE and the Cantillon effect it seems entirely possible that in some industries they could.
To have a true capitalistic marketplace ala Adam Smith, you need government regulation to specifically break up oligopolies: companies which get so large they can collude and price-fix. We call these laws anti-trust laws.
In the US particularly, anti-trust laws are recklessly unenforced, leading to exactly this situation.