Counterintuitively, “M” means one thousand, not one million (which is represented by “MM”).

However, I’d argue this is a thing where it’s confusing to the majority of people and it’s the language that needs to change, just like flammable/inflammable (both of which, also counterintuitively, mean “will easily catch fire”).

Edit: also yeah I agree with folks here – this appears to be an attempt to satirize Zuckerberg in some way I don’t understand