Why did Dryden menace to kill Han and Chewie for not delivering the coaxium the first time they met? They had no deal with him, they were just joining the discussion as guests, or as Beckett's co-workers.
Vos is an evil, psychopathic person who will kill you rather than ask twice. They were on the team, with Beckett, so they share in the failure. That's more than enough for Vos. It's also exactly what Beckett expected.
And Dryden answers to Maul. So if the job goes south, Maul will expect that the people who messed it up are offed. It's part of the be ruthless in a ruthless world deal. Probably how Crimson Dawn stays on top. You either deliver for them, or you die.
Dryden was an interesting character since he was more classic Mafioso or Bond villain than typical Star Wars until he makes the classic movie bad guy mistakes. He really sealed his fate in the end with his weakness for Qi'ra and underestimated Beckett, Qi'ra, Solo along with. Qi'ra was brighter than Dryden cause Dryden was driven by his emotions. Qi'ra kinda followed her ambitions and followed the training that Vos had taught her(he was taught by Maul). All of that not getting emotionally connected, exploiting your enemies weaknesses, and killing someone more powerful to gain their place ect. Working behind the scenes and behind others is typical Sith. The Crimson Dawn Maul structured to mirror his own background in pretty much all ways, the Sith Order. I tend to view the Crimson Dawn like Flemming's Spectre. I think even in some older Bond films Spectre even had their own jewellery. But I think the movie started really fell apart on Savereen as tit had no real climax like Rogue One or any other Star Wars film. It became so low budget, rushed and too predictable little skirmish. Dryden's Enforcers and the Cloud Riders were both stupid and lame. They should've had a big battle with Saw's men, the Empire and Crimson Dawn all fighting to get the Coaxium or something.
No, not every film requires a massive Avengers-style battle at the end (or even something on the scale of Rogue One, which was huge (and hugely appropriate and satisfying for that film). I liked the smaller and more personal scale of the Solo conclusion, as it fit the scale of young Han's pre-Rebel life. In any case, I imagine ESB would get the same reaction among some today: small, low-budget ending . Lando's mall cops vs. stormtroopers. Etc.