Just as a counterexample: revolutions have been spurred on by the need to stop military conflicts and territories not advancing quickly enough relative to other countries. What you always see are demands by a section of people that evolve into movements, like that of capitalists to transform the peasant class and employ it.

Revolutions are not one-sided phenomena. They are not merely riots in the street carried out by the most impoverished. Capitalists themselves are moving beyond the demands that defined their class two hundred years ago. In the United States they are moving away from competition as a pervasive principle to very intentional centralisation. There has been a push to abandon antitrust legislation. For the individual capitalists this is needed and a logical step, but it fuels their own demise long term when it becomes a societal trend. You only need a comparatively tiny spark from below release the potential energy accrued by capital.

What you have in mind are certain narratives on the French revolution. Conversely I can ask why countries that experience famine or affordability crises don't experience revolutions.