Fear of being killed. Unlike the 'clean wars' people've been shown on TV and media, ANY wars is a dirty war. Nothing stopping you from shooting your squadmate in the back of their head and claiming it was the enemy who did it. Not to mention, soldiers will both get desensitized and getting 'war high' which are coping mechanism to dumps their guilt towards another party, making these kind of realization that they're on the wrong side comes to bite back waaaay later until they're a vet (if they survived) in form of PTSD.
Fear of being killed. Unlike the 'clean wars' people've been shown on TV and media, ANY wars is a dirty war. Nothing stopping you from shooting your squadmate in the back of their head and claiming it was the enemy who did it. Not to mention, soldiers will both get desensitized and getting 'war high' which are coping mechanism to dumps their guilt towards another party, making these kind of realization that they're on the wrong side comes to bite back waaaay later until they're a vet (if they survived) in form of PTSD.
The OTHER side. Historically, traitors and turncoats are NOT regarded well.
In this case, there wasn't anyone left who wanted to switch sides. After a full decade of constant propaganda, the Ordnungspolizei, and gradual indoctrination (especially after the Malicious Practices Act made it a felony to criticize the government, punishable by potentially being sent to Dachau) that included ridiculous amounts of peer pressure, social shaming, snitching, and public spectacles...most Germans were either totally indoctrinated or going along with it all because they KNEW what would happen if they didn't. At that point everyone knew someone who knew someone who had "disappeared" courtesy of the Gestapo.
As for the MC in this picture, he looks like he's regular Wehrmacht, not Waffen SS. A lot of regular soldiers only fought in the war because they were loyal to Germany, NOT "der fuhrer". However, the SS watched EVERYONE. Being accused of cowardice was an actual crime, and being suspected of treachery not only doomed you but ALSO your family who'd also face retaliation as well.
That's why so many Germans stated they were "just following orders". Because they KNEW what would happen if they didn't obey: someone else would HAPPILY do it instead in order to elevate their rank within the Party. And the disobedient one would disappear.
Addendum - Another factor that added to the culture of brutality and desensitization was just how utterly corrupt day-to-day life became in Germany between 1933 and 1943, especially in the legal system. While Nazi society became very orderly, it was based on a policy of absolute control. Judges and defense attorneys had to be Party approved. Judges were required to enforce "unwritten Volkisch law", which meant passing whatever sentence the Party wanted. When "Der Fuhrer" came to power, only three crimes warranted the death penalty. By 1943, almost four DOZEN crimes carried the death penalty. The minimum age to be tried as an adult (and potentially sentenced to death) was lowered to 14. The primary means of execution were beheading by guillotine and hanging by strangulation (meaning they didn't break your neck).
Things got really bad by 1942 when the Volksgerichtshof (People's Court) was established to deal with suspected traitors. Made up of two judges and five officials (from the Party, the SS, and the military), it declared suspects guilty almost all the time in sham trials that were all for show.
By 1944, SS-sanctioned vigilante squads began to roam the country, acting as judge, jury, and executioners on the spot.
As for actual criminals, a lot of them simply joined the Party and found legally-endorsed or even sanctioned versions of their crimes. For example, actual murderers and serial killers could wind up being recruited into the SS Death's Head squads. As long as their victims were people other than Germans, the military didn't care.
Add in the shortages, the rationing, the constant "charity collectors" (all Party-run, meaning it was an alternate form of taxation), and everything else...the vast majority of Germans were too busy struggling to survive in a country that had become obsessed with micromanagement and double-standards.
Thank you for explaining in this particular case why in general I'll never join sides to any war (a galactic war could be an exception... maybe). I'd rather rot in prison or be a fugitive over any country than taking other lives in my hands just because a politician told me so. Yes, that includes Putin and Zelenskyy.
My body could be imprisioned, but my conscience will be at peace and my mind will be free... unless they try to torture me for being a coward not dying for my country. Then I would have to resource to something else, yet it's still the very last option. I'm glad I live somewhere not in global conflicts/interests anyway.