This is a really good ambition. I think if they can push themselves to meet this target from their present position, they will surely surpass it with a little more effort.
The fact that VitalBet is one of the only sports gambling website which accepts cryptocurrency as a payment, with this in mind; I think it's very possible to hit the top 15 world betting sites as long as the engine of the site works well. I haven't seen any other bookies which accept crypto
You're right, that's the uniqueness we're talking about, that sets them aside from others and that gives them that ability to stand out form others, the stated bookies like you said still uses fiat currency, Gifcoin stands the chance of been successful, imagine them hitting the top 10 range with such concept, well, only time will tell