Actually, we've funded lots of things that we don't directly use. For example, we funded the development of OPAM, which we don't use internally at all. Moreover, the funding of OCaml Labs was aimed broadly at improving the OCaml ecosystem, rather than just addressing our narrow internal needs. Our work and funding on compiler improvements like Flambda is aimed at things we want, but they're also of broad utility to the users of the language. Merlin is another example of something we've supported that is useful to us internally, but also useful more broadly.
This is of course self serving in the sense that we think the OCaml ecosystem is important to our future, and so we want to help it flourish. But it's a relatively enlightened form of self interest...