Not that I was ever interested in being military, but I was at a lunch with two older lifelong army retirees. They kept talking about how military service broke their bodies and politicians won't cover their medical costs. These injuries were independent of any combat: It's just expected that you sell every part of yourself when you sign up.

Who wants to be 45 years old with a limp, be unable to hear a quiet conversation, and have horrible back problems?

I mean you can look at Russia as an example for how much of the economy was hurt by forcing people out of normal occupation and into service. You also have too look at their abysmal attrition rate to see its unsubstainable and if used primarily leads to worse and worse outcomes on the battle field as they less and less qualified personnel.

Appealing to morality is probably a lost cause for someone supporting a draft, they have already bought into war as a solution. Like moral arguments that Russia is choosing to sacrifice millions and set back their region is something they are already choosing to ignore, forcing people to do it minor in comparison.

Let's start with the second part of your question? How do you make someone understand that invading another country is not a good thing?

Ask them to do so themselves, voluntarily.

If they refuse, the argument stands.

If they accept, you won't convince this person.

Issue is that "old people" had to spend their time in the army, sometimes even in a foreign land (Good old time of the colonial war), so kids these day feel so privileged

I mean, we can blame the boomer for a lot of thing, but in the 60's and sometimes 70's (In many countries) young men had no option but do a military service which way involved going to fight to keep the colonies.

War is horrific. If we deem a military is necessary to a peaceful society to protect from threats both domestic and foreign, then we should have a draft of ALL able adults, not just the poor and underprivileged. Rich folks, political folks, and otherwise connected individuals should be subject to be put on the front lines right next to the rest of us. What that means is we might rethink, as a nation, any military action. An all volunteer military would be the next most preferable one that is paid equal or greater to the national average income with full lifetime benefits including healthcare for the whole body including mind, teeth, eyes, etc., pension, free education including masters and doctorate level education, housing, as well as meeting other basic needs of life.

Anything less than that should be unacceptable.

In most cases, The people have been indoctrinated by propaganda and it's been reinforced by their friends family neighbors local government officials. They're seeing this as good versus evil. Be it forced draft or abortion bans. You can't talk somebody out of brainwashing. In most cases they will never change their minds until they find themselves on the s***** end of the stick. When their children get drafted or die in the military, or the wife gets raped and impregnated, they say this is horrible and you go wait weren't you telling us you felt the other way? And they go I just didn't know. But they did know people told them they just refused to believe it. You're basically trying to fight religion with reason, and you can't do that.

Its a tough one. A pro draft stance I have only seen with the extremes. Usually with the right its nationalism related, real x should be eager beavers when their time comes to serve. On the left its hey the sons of the leaders and the leaders themselves should have representation in the ware zones. I sorta get the last one as we have an all "volunteer" force that has benefits for signup akin to if you coutry had somewhat decent social safety nets along with training and decent pay. So it has no real draw for the well to do. Thing is that when there was a draft the kept their cowardly progency out with things like bone spurs or such. So they had docs make up medical excuses while they called the ones who were plucked to go die suckers and losers.

Federalist Paper 29

The founding fathers thought that standing armies make any leader a tyrant.

You put the someone in a re-education camp

You hold up your draft card and burn it.