Why did the big bourgeoisie not strive to join the ranks of the Cadets?

One of the important reasons was the difference in the social composition of these political forces. The bourgeoisie consisted of the so-called “qualified” intelligentsia, large commercial, industrial and financial figures, due to which the party’s orientation was rather conservative.

Also, the Octobrists (which included the bourgeoisie) and the Cadets perceived the very essence of the monarchy in different ways: the Octobrists saw the State Duma as a legislative body whose decisions had to be approved by the monarch; the Cadets, on the other hand, were fans of the parliament being endowed with unconditional legislative power.