The crowd believes in Barcelona, the bookmakers are forced to adapt to this opinion, because if they give honest quotes for the game, and because of the dispersion of the results, the crowd is right, then the bookmakers will be at a loss. In general, I was once again convinced that Barcelona is very much overestimated (only one point was scored out of three serious games) and I look forward to Clasico with pleasure.
To be honest, Barcelona's performance in the Champions League was great, but somehow they struggled to win 3 match in a row so far. They may have been unlucky with the group draw this season, but that's not a good reason to justify assumptions about why they failed.
Bayern Munich and Inter are apparently still very strong for Barcelona, so it would be better to expect them to come home sooner than fall short in the last 16 against the likely title favorites this season. Barcelona have very little chance of qualifying, it's probably around 20%, and the rest they will probably head for the Europa League.
To be honest, I don't know where you saw a good performance from Barcelona in the Champions League. The fact that they had chances to score a goal against Bayern and against Inter also does not mean some good achievement - every team has missed chances. Yes, Barcelona did not lose all the games with a crushing score, but all the games were lost by game - in general, it is clear that Bayern and Inter are simply stronger than Barcelona.
And yes, the bookmakers give about 16% for the fact that Barcelona will still be able to reach the playoffs. For me personally, it's amazing - Inter should beat Victoria, Inter can beat even unmotivated Bayern. While even an unmotivated Bayern can beat their favorite principle rival - Barcelona.