So yes, businesses - especially small businesses - are important. And serve the country.
Requiring military service would absolutely kill some careers and remove enthusiasm and even hope from some young people. For example, in the hard research sciences, one's most creative years are the very early ones. And the long, difficult, extremely focused education requirement does not adapt well to a few years out of school in the military. I went the research science route, dedicated 9 years in higher education, got an engaging and rewarding job, was compensated well for my talent and paid $50,000 each year in taxes for 18 years. Some of what I worked on is being used to save lives in the military and my tax dollars certainly help the military consume up to 1/3 of our national budget.
None of that would have, nor probably even could have, happened if I was forced into military service out of high school. And there wouldn't even be a military or much of a country without higher education and a very large tax base to advance the technologies and support the cost.
I have a right to consider myself as having served my country, and Tom does too. More so than serving a few years in the military sweeping floors or filing papers - which, let's be honest about it - is what the majority of people will be doing if everyone is conscripted into the services (many are used for just that in the present services).
Unless we use that flood of young people to start several more wars. You aren't suggesting that, are you?
Mark