This is what Russia is (semi-successfully) doing.
You either need to firewall the nation (which I imagine would be pretty unpopular) or it's just a waste of resources.
VPNs are incredibly easy to spin up, gambling groups are not. Within a week I could probably spin up a dozen or more semi-legitimate VPN companies. Multiply that by however many hundreds of people are willing to do the same. Add a few thousand more people willing to spin up completely shady 'free' VPNs.
The scale quickly exceeds what you can possibly block, unless you firewall the nation.
The article that our comments are under are about an 18x increase in sign-ups from the UK for one provider, a 2.5x increase for another provider, a 10x increase for yet another provider, etc. in just days.
I'm curious about your stats for China/Russia, though. Where/how do you find out how many internet users in those countries have a subscription to and/or use a VPN? Would those stats continue to hold true if there was not a great firewall in China, and just rudimentary IP-blocking of VPN providers?
Those numbers mean nothing without the baseline. What if before it was 1 person and now it’s 18x more, totaling 19 people?
W.r.t. data about China and Russia, I don’t want to pay for market reports, but occasional discussions about China, for example, show that about 35% of internet users use VPN (https://www.reddit.com/r/China/comments/i3afnz/how_many_peop..., the thread has some links for more info). However, it is unclear how many of those users are private citizens use VPN to specifically bypass censorship. From my anecdotal experience from work and my PhD, most Chinese I met just don’t care about censorship and lack of access to FB, YouTube, or whatever. Chinese are like western users for the most part, on average they need social media, financial apps, maybe search, etc. they are not actively looking for censored info.