During the Cold War, Soviet states and the socialist economic system they had were propagandized in America as "the government can take your stuff at any time because COMMUNISM". This was aided by the fact that, in practice, the Soviets could and did do that. However, it was not at all a
unique feature of socialism or communism. Police states don't care about who nominally owns the economy, they care about what can be looted from it.
Capitalism has no defense mechanisms against unwarranted seizure of property. Private ownership is a precursor to capitalism, not a byproduct of it. Furthermore, there are plenty of ways by which capitalist entities can gain government-like powers, if not totally supplant the government[0]. Concentration of wealth is a problem whether or not the person who owns the wealth claims to own it for themselves or in the name of the working class.
The way that you prevent the government[1] from stealing your stuff is to make it inconvenient for them to do so. In the US, we have presumption of innocence, right to due process, and so on. These are constitutional rights that the government broadly respects. If they regularly didn't, you'd see brain drain as people and businesses with the means to do so would escape the country. Those without such means would begin economically sabotaging the country. However, these are blunt instruments whose use entails personal cost, so people don't use them right away. The US can therefore get away with ignoring its own constitutional obligations some of the time, and in this case, that's how they get away with civil forfeiture.
Think of it like this: when Apple or Google start screwing over developers, or Reddit or Twitter start screwing over users, we don't all immediately jump ship, but some do. If they continue doing this, and they exceed a particular threshold of bullshit, they continue losing people faster than they gain. This creates a feedback loop of stupider and stupider tactics pissing off more and more people until the platform collapses.
Countries work in similar ways.
[0] The basic idea of Rothbardian ancap economics is that we should deliberately encourage this. The idea is that this would supposedly lead to competition for governance. Except this wouldn't actually happen because competition is a byproduct of capitalism, not an essential property of it.
[1] or government-like entities