Among my family and friends there are two very different views. Some think the celebrations are a welcome and much needed treat for us all after a really grim couple of years. Those (the majority) who are not royalists see it as a lovely excuse to eat, drink and be merry. They are unconcerned about the costs.
The other view is that it's just adding insult to injury and it's totally inappropriate and divisive. Our essential safety net, the NHS, police, social services, local councils etc. are all really struggling to cope - along with a large section of the community, who simply can't make ends meet, let alone afford to party. They're worried sick about the future and would prefer that any funds go to the needy.
I can see both as valid reactions. Although not interested in royalty, it's a historic event, we can choose whether to celebrate/participate or ignore it all.