The main reasons I’ve heard thrown around for this are: 1) Autism-spectrum traits correlate to being trans (why? nobody knows) and also correlate to high technical ability, 2) tech is generally fairly accepting of alternative lifestyles and identities, 3) if you were brought up as a boy you probably had more access to computers and were encouraged to go into that field, 4) if you were brought up as a boy but were actually trans, you probably preferred nerdy stuff to sports and computers were a good distraction from hating your body, 5) tech jobs have good healthcare.