Actually extremely not true.
This misconception exists because if you have a room full of 500 mega rich and out of the 500, 5 of the top richest 200 are very loud, vocal Democrats, then naturally those five democrats are going to appear very obvious and influential because they are 5 loud liberals out of a room of 495 mega rich conservatives who are all probably giving attention to those 5 liberals.
Anyone who thinks there are loads of mega rich Liberals clearly has never lived around such people. They are not liberal. Then again it's another world that's very separated from most of us so this error is understandable.