It's still a lot. Mastodon has grown enormously. If Twitter keeps burning and Mastodon can handle the influx (the latter is the bigger 'if' here), that it may continue to grow.
>>mcv+(OP)
It's entirely possible (although I personally think it unlikely).
Regardless, < 1% is not a lot of Twitter users by pretty much any stretch. I think people in tech or fringe communities are seeing a high uptake in their own groups and assuming that to be reflective of Twitter users at large.