The power of the largest big tech companies will continue until the government decides to use its antitrust powers to break them up. How they got where they are is perfectly legal - but when you have a super high concentration of market share plus inability to enter the market you have a classic natural monopoly/duopoly.
You get into these situations through perfectly legal means (better in the market), but eventually the market power can become so great they get monopoly powers.
The USA has had the same sort of thing many times in the past - and only antitrust powers can mitigate it. Classic examples were railroads, the old AT&T monopoly on long distance, and steel.
This is the sort of thing that Biden cares little about and Trump cares a lot about (because Trump thinks it is being aimed at him personally). But the concentration of distribution power on phones (apple, google) and social media power (facebook, instagram, twitter), and general retail (amazon) is so high that you need antitrust to maintain competition.
