All these bad reviewers need to realize two things.
1) You don't know Boba Fett, you only ever saw him interacting with one of his clients in the original trilogy for five minutes. Would you be annoyed if someone was trying to predict what you "would do" after watching 5 mins of interaction with your boss? It's annoying. Stop it.
2) Give the guy a break. He just suffered an ignominious near-death experience where he was trapped inside a creature, being slowly digested, and only narrowly managed to escape by inhaling who knows what from a dead stormtroopers suit.
Then after burrowing through Sarlacc and dry sand for who knows how long, when he finally gets out, he's in the middle of the Dune Sea at what appears to be midday.
As if that wasn't bad enough, a bunch of Jawas - who probably know who the famous Boba Fett is - rob him of his armour and knock him unconscious, leaving him to bake in the desert suns.
Then he gets taken prisoner by the Tuskens, and made a slave labourer, subordinate to the lowliest member of the tribe, who beats and berates him mercilessly.
After showing the Tuskens that he is a fierce warrior in his own right and saving his captor, Boba is accepted as a member of their tribe, given a fighting stick and robes in a special ceremony, only to return and find the entire tribe brutally murdered.
He's had a bit of a rough time lately, and plenty of time to think about how his life choices have played out, plus he's (literally) not the man he used to be before his encounter with the Sarlacc.
So we have a guy who has only five minutes in the canonical films, who has had experiences that could change the perspective of even the most hardened individualist.
Even if you did know Boba Fett somehow, you don't know THIS Boba Fett, the guy who has decided to do something with his life instead of just being the baddest guy in the room until he wasn't.