If you didn't have assets worth at least one million sesterces you were removed from the Senate by the Censors. Basically a game over for a Roman that wanted to make his name.The guild is more about money, thing less important to Roman patrician. The focus here need lie elsewhere...
So wealth mattered a lot. On the other hand the system didn't always work and Caesar was a senator (and even got governorship of Gaul) despite being heavily indebt. In his own words: "I need at least thirty million sesterces in order not to own anything".
No it was stored in real estate, great estates of the patricians and other property not cash on hand. It, obviously and as always, mattered but prestige mattered more.
Basically one you did qualify for the senatorial class wealth was just an afterthought.