Many people here are talking about how more powerful people are also corrupt and are getting away with it. All corruption is bad. This soldier put the life of everyone on the mission in danger by doing this.
This is true, just like "all lives matter" is true, and it misses the point in the exact same way.
Those people you are replying to are not saying that this soldier should get away with his corruption because more powerful people are getting away with theirs. They are saying that those who abuse greater power are doing greater harm, and that their corruption should be punished with greater urgency.
On top of the harm the powerful people inflict directly through their corrupt actions, there's a secondary effect on the society at large. Unlike trickle-down economics, trickle-down corruption is a real thing. People see those in power get away with corruption and say "Why should I do the right thing?"
Of course, the usual answer from those in power ends up being "because we have the power to punish you and you don't have the power to punish us". And that's how you end up with the arrest and prosecution of a US soldier on the same 5 counts that the top politicians and their cronies are getting away with on a daily basis, aided by the president himself.