Finally got through season 4 of Billions. It seems to be getting more than a little silly in places - but strangely is no less watchable for that. The good news is that Season 5 has been confirmed. Huzzah!
Billions is one of those shows I fear for - a great story in the first two seasons that may not have an ending in mind (as opposed to a certain series that always had an ending, but lost the path and required deus ex machina to reach it ...). As you said, however, it's fun viewing - like the stopped-in-the-nick-of-time "final solution" for the chicken futures.
Other fun shows: Season three of Stranger Things (Netflix), Godless (Netflix), Altered Carbon (Netflix); Big Little Lies (HBO), Sharp Objects (HBO), Los Espookys (HBO), Barry (HBO).
I am waiting for the next seasons of Peaky Blinders (Netflix in the US), Penny Dreadful (Showtime - new storyline set in 1930s Los Angeles and Mexican folklore), and Westworld (HBO - had big hopes after the first season, but the original creators effectively stopped running the show after the second season got into some serious but interesting/confusing weeds).