When I was a kid, I used to like fantasising about being the winner of one of those competitions where you get to run around a store with a trolley taking whatever you wanted. You obviously get a limited time, so strategy would be everything. Do you head directly for the things you like most, or do you head directly for the things people in general like most? Obviously you only know what you like, but you also have a sense of what other people like because of the price.
One strategy would be to head for the smallest, most expensive things. As long as they aren't on the other end of the store and you waste to much dead time reach them. So you have to aim for the smallest, most expensive things that you can get to the quickest. That is still not enough though. Often small, expensive things are in part expensive because they are new and because they came from a shop and because they come with follow up service. How are you going to resell these items? I once got very excited when I won a big box of stamp pads at a tombola. No matter how talented a salesman I may have thought I was, technology had progressed so that stamp pads were not that common an item of desire.
So perhaps the best trick would be just to ignore getting the most possible, and just run around getting stuff you like? Pile up on sweets. Pile up on CDs. Perhaps the odd ridiculous appliances that you wouldn't have been able to justify. I hear that the Thermomix will change your life. Grab one of those if you can. But if you are ten, you are probably not thinking of what will save you the most time as a factor of happiness. Arguably the single machine to make the greatest contribution to the happiness of the world has been the Washing Machine.
There are big problems with this scenario of rushing around. (1) You are 10. Sweets and electronics probably dominate your thoughts, (2) You are in a rush. You can't slowly and carefully consider all your options with detailed analysis. You have to act. (3) Whatever aisle you are running down and whatever catches your eye will probably win.
I don't think life is different from this challenge. If you watch little people becoming bigger, their emotional intelligence growth is more on display than what is going on in their head. That growth doesn't stop at 18. Our decisions stay emotional. We have a limited amount of time on earth. Too short to understand everything. We don't have enough time for the things we want to do. There are always trade offs. The choices we get to make depend on luck, the choices that have been made for us, and the choices we have made. 'Revlon moments' are bound to overrule any grand plans you have, ignoring the budgeted self control because you deserve it.
At the end of the day, you just have to remember how lucky you have been to have won the competition. That is already awesome. Smile, and thank your trolley.