Every bitcoiner must have been risking in gambling before Bitcoin was invented. Maybe as bitcoin was birthed they decided to stick with bitcoin trading and investment and say bye to gambling. In conclusion, every bitcoiner must have gambled at a particular time but not all gamblers know about bitcoin.
That's a valid point. Even before bitcoin or the whole crypto in general was commenced, there are surely bitcoiners (or whatever you called it) that are already involved in gambling. Now learning the advantage of using crypto in gambling, others shift their gambling habit from the usual fiat gambling into crypto gambling.
Referring to bitcoin trading and any other bitcoin-related investments, these are just an added option for these crypto gamblers if they are interested in doing so. There are crypto gamblers who also involved themselves in trading while others just remain focus only on crypto gambling.