I feel like we could better spread this idea if we removed the verbiage of communism from it. I think you would convince more people this is the truth if you worded it more like:

Allowing a few individuals to consolidate wealth gives them a sort of power they can use to bend the rules to their favor which furthers their ability to consolidate wealth which gives them more power, so on and so forth until we are where we are now

I feel like more people would agree with this, whereas talking about taking "surplus value from the worker" will automatically turn off peoples interest in hearing anything from you as they've been trained against this kind of phrasing.

I think you have misunderstood the definition of corruption. That aspect of capitalism might be considered unjust, but corruption has a different meaning. The ruling class might use their gains for corrupt purposes, but that's something that can happen in any system with a concentration of wealth and insufficient regulation, it's not inherent to capitalism. You might want to take a look at social capitalism