That's called business competition. Stay in business by delivering greater value.
It's likely the maintainer is in the best position to start a company about the product to deliver more features faster and at higher quality along with more inherent trust.
As someone being in a similar situation, it's a really difficult business model. Unlike many other business models with a natural moat (i.e. by virtue of having all the data, being deeply integrated into organisational processes, etc), commercialising open source is a struggle because simply justifying making money already requires constant improvement.
It's likely the maintainer is in the best position to start a company about the product to deliver more features faster and at higher quality along with more inherent trust.