Whatsapp doesnt allow you to send money which getgems does, which is more powerful than encryption imo.
It depends if you care. If people want an end-to-end encrypted app with massive user saturation then Whatsapp has a huge userbase head start, and now that it is free is growing very quickly.
There are tons of ways to send people money electronically where you don't have to deal with some Fiat to token exchange in addition to sharing the same app with the receiver, etc.
I hope GetGems becomes huge, but it has to find it's correct niche and market hard there. Because secure end-to-end messaging is not the "killer feature" that will get people to switch.
The most likely opportunity to grow the userbase for the wallet feature is to convert Telegram users to GetGems with the "Chat with your Telegram network PLUS this, this this".
EDIT:
Whatsapp: 990 million users, 320 million of them active daily, 1 million new per day
Telegram: XXX? millions user, 65 million daily active, X? new per day
I couldn't find the total telegram users or new per day numbers.