People around you are there for the benefits, so don't expect enthusiasm or professionalism.
Everyone is a Senior Software Engineer—even people who absolutely aren't.
If you have a good idea, your manager will tell you it's a bad idea, and six months later he will present the same idea to others as his own.
Your tech lead will use the project you're working on to pave his career path, forcing his ideas down your throat, even though the entire team thinks his ideas are bad.