The figure might be misleading. It might not be. Either way, the idea that the natural and normal state of affairs is that every person can go out into the world and be a perfectly self sufficient but comfortable atomized economic unit without support from their family or society is deeply flawed. This wasn't the norm for most of human history, and it isn't the norm globally today.
Look at the comment above, the sample is from really wealthy parents, not the median income in the US, so I'm sure that skews the data.
That's quite different to your claim.