If you have an orchestra with 100 musicians who receive something like $10^5 per year, you pay $10^7 per year. You need several years to practice and to form the orchestra into a team with a repertoire. If it takes 10 years, then that is $10^8.
No you don't. Orchestras come together and perform completely new works with, if they're LUCKY, 1 or 2 rehearsals. Years of practice is completely ludicrous.
Your numbers are grossly off here. I would bet that zero orchestra musicians are making anywhere close to $100k just from playing in an orchestra - the absolute top of the top might make that across all of their engagements. Most are making far, far less.
In good orchestras in the US and western Europe, $100k is actually fairly standard, perhaps even on the lower end. You need to be highly skilled, the competition is fierce, and the job is very demanding.
I don't have a good source, but a quick Google search should confirm that $100k is not exactly wild.
In software it can cost $10k to build an app but Google Search costs $10^10: a six orders of magnitude difference.
In music there’s got to be a big dynamic range in effort involved as well. (I doubt it’s 10^6 though!)
But comparing the best music to the lowest end app is apples to oranges.