Because it came out like 2 or 3 months after The Last Jedi came out, and that movie was a gigantic turd. So fatigue was a factor, the prior movie being complete ass was a factor, and honestly I don't think Star Wars has done a very good job at hyping its last couple of movies up. I feel like previews and stuff just have not been there leading up to these movies. I vividly remember not hearing anything about Solo coming out, then all the sudden hey a new star wars movie with young han solo is coming out! In like a month! Anyway, another factor is people love to hate on social media anymore. TLJ legitimately deserved to be criticized to the max, but that criticism just kept coming and coming and it piled on to Solo for no other reason that TLJ just sucked so bad that nobody had any confidence this would be better.I thought it was an entertaining movie, and perfectly fine. I don't know why it didn't do well.