A loss of endorsement deals probably has little to do with anything nowadays. It’s more about being worried about traveling in overtly homophobic/anti-queer countries. And while players talk a big game to the press, there’s the fear of being ostracized by a percentage of players. You also have whether you come from a religious or hetero expectations driven family. You also have internalized phobia, toxic masculinity, making sure you’re seen as a “real man”. Then there’s potentially dealing with dimensions or fluidity or contractions or not really being confident in where you are in the gender, sexual, affection, romantic, emotion, commitment spectrum, which can make it difficult to be confident in your sense of self and how you present yourself to others. Then there’s the fear of being “out” eating up your whole image and being what you become most known for.
Just like when it comes to non public figures, there’s a lot of reasons why athletes stay closeted or simply don’t express their queerness publicly.