What is influencing the growth in the number of traders?

Accessibility and little funds to start trading with are the two factors I can reference to.

In the past, exchanges and trading platforms weren't as ubiquitous as they're today. Even the few exchanges that were around didn't have the type of exciting offers and inducements as we've them today. I can remember how "normal" and "bland" the likes of Poloniex, Bittrex, Kraken, and a few others I can't remember now, were until Binance came and revolutionized the whole thing. It's exciting now with each modern exchange trying to outdo the other through healthy competition by enticing their subscriber with trading offers and incentives.

More so, as little as $10 now one can start trading.