there are two possibilities, either the big behemoth provides something for cheap (let's say because there's competition or because the buyers form an efficient price negotiation bloc), in which case the buyers benefit from buying from the behemoth (trade! comparative advantage!), or the big behemoth is bad, in which case it makes sense to try to start a company that has similar offerings.

and if domestic companies cannot outcompete the behemoth then it means whatever the behemoth is selling hard to replicate (which is really really .... reeeeaallly rare in software tech, and only non-software companies like ASML/TSMC come to mind, which are more like joint companies funded by and providing to a whole industry) in which case there's unfortunately not much to do anyway - the behemoth's offer might be "unfair", but then by definition it's not competing with domestic companies, it's offering completely different.

(sure, transactions costs matter, subscribers are sticky, etc.)