I'm really glad your son has found activities that he enjoys! It sounds like cadets and music and lacrosse sounds like a wonderful cross-section of experiences for him, very nice!
I'm not sure what part of my post was high horse (; that parents should expect activity costs as part of having children? That you may have to pay for those activities rather than saving the money? Or that I consider it my responsibility to ensure my kids can play at a level that is challenging? Our daughter has grown up and moved out now, but she did participate in soccer, dancing, softball, tennis, track, volleyball, and music (piano). Our son who is a teen now is quite hard into soccer and football.
So an example: our daughter played soccer at a recreation level because she didn't want to be too competitive, just run around with her friends and play the game. That was her personality/ability level, which meant that rec soccer cost us about $60 per season, or $120 per year plus $20 for shin guards, $40 for cleats (at most when she was older), and $10 for team pictures. Total was $190 per year (roughly). Rec soccer has little practicing and generally parent volunteer coaches.
Our son, however, is very competitive and driven - he wants to improve his skills, play at the highest level he can, and compete against people at the same skill level as he, and probably will be a lifetime player. For him to play competitive soccer, the fees are about $450 per season or $900 per year, plus $20 for shin guards, still team pics, various cost for cleats (usually $100), plus he plays for teams that attend tournaments both in town and out of town, provincial championships, etc, for an additional yearly cost of $1200. So his total for the year is $2230. Competitive soccer has more practicing and training than games and has certified coaches.
Now, should I tell him that 'fundamentally team recreation does not have to be expensive' and have him play the cheaper rec soccer? Would it have been okay if I had forced my non-competitive daughter to play the more intense competitive level? I'm betting most would answer no - so why would I force my son the other way?
I completely disagree with your comparison about the eight-year old receives a designer purse - first of all, sporting equipment is required and is needed for safety. If you don't believe that cost makes a difference, go to an expert and ask them about the safety ratings of various pieces of protective equipment and check the cost - they often correlate. I do spend more on my son's cleats for soccer than I did for my daugher's - he spends way more time in them, they are made for the particular surface he is playing on and so give a safer grip and prevent injuries.
And if you are counting in the '3 out of 4' to include 2 parents, then I would strongly suggest that as parents yes, a lot of our 'spare time' does revolve around our kids and their activities. Whether they are organized sports or your family excursions, that is still time spent.
In terms of how to choose, it is what the child enjoys, what they thrive on, and what is within their abilities. Yes, my son could not play high school football because it would time conflict with high school soccer, so he opted to play for the minor football league instead. They have to learn to make choices like that, not just have the parent choosing for them on the basis of how much it costs. We spent money on our kids activities as needed, and if it would have been something we could not have afforded or not been willing to spend (like the $50 thousand, which I am sure even you will admit is the far, far, far end of the ridiculous extreme), then we would have told them that. We can't afford it.
I don't know how it is in BC, but here our preschool was pretty cheap. We've been putting away RESP money for both kids to cover tuition and fees for college. I don't see that as a detriment to paying for our kids to participate in activities though. And frankly, if I had to choose between an activity for myself and my kids, I chose the kids. I can do my activities when they are grown up and gone, which happens all too quickly.