> I don't know what the bias is called but there is this belief that many successful people have or try to bestow that they "did it all themselves" and "you can too".

This is a combination of egocentric bias[0] and post-hoc rationalization [1]

[0] https://en.wikipedia.org/wiki/Egocentric_bias

[1] https://en.wikipedia.org/wiki/Post_hoc_ergo_propter_hoc