Luton offered lots of opportunities for Brighton to score, 27 or so, and showed they won't play conservative against better opponents on paper, that they will go and attack, and probably should lose by many goals.
On the other hand, Chelsea always invests like 100M to make a great team on paper, and in practice they struggle, like their last year 12th place and their 14 games with a single win and low scored goals show us. They last defeat against West Ham raises some concerns, but play West Ham at their home is tricky and they sometimes cause upsets, and Chelsea did dominate the game in the first half, with their missed penalty being a turning point for the worst for them.
In the end of the day, it is a game to be observed, not to make bets on, in my opinion. Will Chelsea keep disappointing their fans and giving crap results again even after investing a fortune in the team? Will this game be a turning point for them?
Or will Luton cause an upset and maybe even change tactics and be more conservative against the big teams? The small teams that get promoted sometimes do cause upsets, and Aston Vila did re bounce  after their thrashing against Newcastle in the first round.

If Chelsea plays OK I might add one of their players in my fantasy team since they have some easy schedule ahead, but I will observe first.