Marxist are not born Marxists. We were liberals, we went through all the ideologies and convictions that you yourself reside in at this moment. I was a rightwing liberal, social liberal, Nordic social democrat and so on. It was through self-criticism that I forced myself to read more, to listen more. To question more and to think things through. Nordic Social Democracy sounded like heaven to me and it would still have sounded like haven if I would have build a bubble around my convictions.
Instead of doing that I started actually listening to people that lived in those societies, where I discovered the benefits and the downsides. Most importantly I encountered that they too have the same essential issues that you can't escape in Liberalism.
Capitalists are like cats, they will eat you once given the chance. Thanks to fluctuations in activism and participation, the weak moment always arrives for the working class and capitalist will and have to use that opportunity to strike back. They have to because they work in a market system, either they seize their opportunity or get out competed. Europe is the prime example and in 50 years will be more like America today if we keep up this path for this very reason.
-Marxism builds on the theory of liberal capitalism and acknowledges the purpose of the system, its benefits and its flaws and then tries to use the thesis and its antithesis to create a synthesis, which is socialism. After which another thesis-antithesis is needed for communism.
-Marxism was significant because it was non-utopian, where both Liberalism and Utopian Socialism were founded on an ideal. How many times have you heard 'this is not who we are' and so on from Liberals and Social-Democrats? Marxism counters that with materialist analysis.
Marxism throws away the ideal as basis and tries to take the root, the power ratios in political economy and create a society that marches towards upholding humane living instead of ethically hoping on achieving that.
To conclude:
We would love for it to not be needed. We would love to be able to stay home, vote once a year and have everything work out just fine without system change.
It is simply that we rationally and scientifically concluded that that is not possible, were are not crazy radicals just to stand out. Some are I suppose but the serious works written in the past one hundred years are completely air tight in argumentation.
Reading suggestion is Reform or Revolution, by Rosa Luxemburg. Yes it is old but the arguments in this thread are old, too. That book will change anyone from a reformist to a revolutionary because it will deconstruct everything that you have build up as truth up until today when it comes to political economy.