You can be a righteous man and still get drunk and depressed.
At this point Chris has spent 15 years seeing bio-terror go from bad to worse. He lost the city he lived in, he nearly lost his sister more than once, and he has seen countless colleagues die (including Jill, however temporary). Add in the fact that despite stopping major biohazards, Chris isn't really getting anywhere; some other psycho always comes along to try and destroy the world.
We'd all be drinking away our sorrows too!
Science! Has science ever kissed a woman or won the Super Bowl or put a man on the moon?
The poor guy has spent the last 15 + years fighting bio-terrorism, has lost countless friends and solders over the years due to bio-terrorism, had to watch his entire squad of soldiers get infected (In astern Europe) and mutate right in front of him while he could do nothing about it; then he had to put down said infected soldiers, and he believes that he failed in his mission 6 months previous to the start of RE 6 due to him failing to capture the mysterious women (Possibly Carla or Ada, or a clone, or ... whatever) whom by the way killed over 150,000 people while experimenting upon them over the years. Yeah, Chris has faced more than any 50 people had to face in their lives. Seeing him drunk in a bar really sells home just how much of a toll his job and it's various conditions are waring on him. He still is my favorite RE character even through the years and I love that Capcom is adding more emotion to his character.