Those who have something to lose would not have done it (aka the countries that need the gas, or the country that provides it). Poland is a very interesting idea, since even if they are caught, they are the ones providing the gas to Europe now, and refusing to deal with them is not an option.

Why? At least in Sweden I would say most people are celebrating that Nordstream went kaputt.

That's a rather big claim and I would disagree.

That said, looking forward to paying 20 SEK per kWh, that'll be fun. Also, there's no wooden pellets or firewood for purchase no more - as it's all going to the continent.

Isn’t Sweden insulated from the energy crisis because so much of its electricity comes from hydropower and nuclear?

Sweden privatized its electricity sector. Then several nuclear power plants shut down, in some cases because prices were low at the time and it wasn't profitable and in some cases because they let it fall into disrepair. So Sweden has an energy crisis of its own now. Sweden does have hydropower and wind power, so prices are low when it has been windy and rainy, but prices are sky high the rest of the time.