The alternative is for those 20 people to learn to code, or spread the word that they are looking to pay for an alternative.
A monopoly occurs when competition is actively prevented, in spite of its ample competitive ability. The monopolist uses its power to block the entry of new competition, even if that competition has the product, know-how and so forth. In some cases monopolies are geographical, like utility companies. Another utility company is just as capable, but it and its wiring/plumbing is in another district.
The mere difficulty of mustering a viable competitive effort (e.g. it being difficult to write a replacement program that those 20 people are willing to use instead) is not a monopolistic entry barrier.
A monopoly occurs when competition is actively prevented, in spite of its ample competitive ability. The monopolist uses its power to block the entry of new competition, even if that competition has the product, know-how and so forth. In some cases monopolies are geographical, like utility companies. Another utility company is just as capable, but it and its wiring/plumbing is in another district.
The mere difficulty of mustering a viable competitive effort (e.g. it being difficult to write a replacement program that those 20 people are willing to use instead) is not a monopolistic entry barrier.