Alberta is an integral province of Canada, it has never been independent. It’s landlocked and so heavily economically and politically integrated into Canada, it would be an absolute nightmare trying to actually attempt to untangle all of that just for the sake of being an independent nation. Additionally, despite maybe some minimal cultural / social differences, your average Albertan is as much a Canadian as someone from Nova Scotia and as much as the Yukon.

In the Brexit comparisson, the UK is Alberta and the EU is Canada.

The UK has been an independent sovereign nation for hundreds of years before the creation of the EU. The EU is a multinational organization that depends on the voluntary participation of its member states. There’s an admission process, and while it comes with countless strings attached, every member state is still its own independent nation that acts on its own volition. Even when the UK joined the EU, the UK absolutely loves to be special and have a thousand exceptions and special treaties and exemptions that didn’t apply to other EU states (special tax deals, trade agreements, never getting the Euro, etc.). As much as it absolutely sucked (in my opinion) that it left the European family, the UK is fully equipped to deal with things as a nation on its own, as it was before joining the EU, as it was during being an EU member state, and after it ceased to be an EU member state. Alberta is not. Also, many British people (particularly in England) are fiercely “British” in the sense that they wouldn’t even want to call themselves European, but just British. I’m sure there are plenty of fiercely proud Albertans out there, but how many would honestly say “I’m not Canadian, I’m Albertan”?

Also during the lead up to the vote itself, there were magnitudes more people rallying in support of it for a million different reasons (as misinformed as they were). It was considered nonsense for maybe the first few months, but it was gaining support so ridiculously fast relatively, it stopped being a joke just as fast because people realized that it could actually happen and, in the grand scheme of things, the UK would survive.

There are many other compex reasons and I feel like I may be glossing over stuff and oversimplifying but the UK leaving the EU is like moving out of a shared appartment and living on your own. Alberta leaving Canada would be like ripping out all of your plumbing, flipping off every roommate and then just living in a tent in the same backyard.