Things that need work necessarily cost money. Someone doing the work for free is not inherently sustainable. Profits motivate work to get done all on its own. Profits by definition is money over and above expenses. So it creates a perpetual sustainable mechanism. Competition motivates quality and efficient pricing (eventually).

Lobbying corrupts this a bit. However they are not lobbying to suppress private competitors only government-run competition that has no profit motive or competition. When the government runs it we still pay for it, except now people who don’t use it also pay. Also wealthy people pay a disproportionate share as compared to their use due to progressive income tax.

In theory anyone can start a company if they have a better or more efficient product or offering and get the profits instead.

Thats the rationale in a nutshell.