You may laugh and scoff at such beliefs, but many it seems believe that it was for that reason he acted as he did. Marcus Brutus was indeed a very rich man due to the huge interest rates he would place on loans, but would not the honour and prestige of being Consul in 41 far outweigh that of any minor increase in his bank balance? To the Romans, as you will be well-aware, the position of Consul in the Republic was very important, and to keep Caesar in charge would mean he would indeed be Consul.
And yet he did not. Instead he murdered the man who could hand him the job his father could never reach. Instead he murdered a man who, some say was the greatest General of all time. For money? For greed? He would have become far richer with the prestige and honour of the Consulship.
Cicero on Brutus: 'the courage of a man and the brains of child'
He acted for his ideals, that the Republic was best, and Rome did not need an Emperor, or at least one man in power: the very set-up of their Government was to avoid such things. A man of his abilities of acquiring money could have found other ways to increase his estate, with Caesar in charge, and he himself in the position of Consul.
I found this: "All this was extremely unrepublican, and Brutus decided that he had to act."
The word "unrepublican" is the key here, as it does not say:
"He was trying to preserve the "Republic" at all costs because new reforms introduced by Caesar, were aimed at putting an end to some of these abuses..." - Germanicus
Of course I admit Brutus was tax-farmer, there is no case for saying that he was not. Of course I admit that Brutus was a fool to murder Caesar, and I do not even like the man. I do not think he was a martyr, and the basis for thinking that I do escapes me. But I do think this: Marcus Brutus killed Julius Caesar because he wanted the Republic to stay alive, because he thought it was the best way to govern.