Yes, that same theory that socialism leads to communism also posits that capitalism leads to socialism. So is captalism evil now because of a theory based off Marxist ideas? No.
And again, you're missing my point. Socialism is an economic structure. It has nothing to do with social programs. People call social programs socialist in nature, and they're not exactly wrong but they do not inherently dismantle the free market. Social Democrats are only advocating boosting social programs we have and expanding the reach of education and healthcare. Do I agree with all their polices? Again, no. Do I think there is a nefarious mission to take over the government? No. I'm sorry, I don't.
And nor do a lot of people. And yelling and screaming about the failures of a completely different econnomic structure, calling two different structures the same thing, doesn't make you look like an individual that will cultivate a following of people who question the status quo but fall in line to a new one. Which, I hope you understand, is counterproductive if you're intention is to prevent a communist overthrow (that isn't happening.)
Besides, the government already has stakes in some businesses and industry. Certain services such as military, education, banks, emergency services, communications, research, and health are already heavily intertwined and regulated by government. Even Trump advocates a bit of socialism when he threatens to punish businesses for not keeping manufacturing and trade strictly inside the US. Trump confiscated private property to build his wall. And Trump certainly tries to make it sound like his actions are plans to strengthen the economy. In short, socialism, in theory, is already a fundamental part of the US government.
And there are some things the government should provide it's citizens by payment of taxes. Not just military and not just the indecent money grabbers in congress who make people like you and me do all their argument for them. Healthcare, education, emergency services, social programs, and Military SHOULD be paid by our taxes.
Banks and communications should not. Of course, that is just my opinion. And I completely understand if you have different priorities in those groups. But dismantling them for the sake of reliving debt and letting spending go out of control are firmly what I'm against. And you should be against that too.