@keyser did you get the links I posted above? They are not exactly what I was looking for but close enough. Percentage of tax burden shared by rich vs tax rate as shown in the chart from link above gives reasonable evidence I think.
Of course there will not be proven fact on most arguments. I personally believe that there is sweet spot in the middle but if I have to chose one or other than I will chose very low tax rate that Trump is proposing instead of Democrats who are for very high rate. As you see, higher the rate goes lower their share of burden.
Also, very low tax with high spending is itself a form of tax (regressive tax) as government will try to outgrow the debt by creating inflation. Rich will invest in equities and other assets which protects them and its poor who will have less accessibility to housing and other basic needs. But again, this is one of the sad reality. I hope Democrats will stop pandering to ultra left in next cycle and be there as a viable alternative. Biden personally is not a bad choice but as I have been saying he is too weak (mentally, physically, and politically) and will leave white house to either Kamala or Susan. He will cave in to Squad team. I hope Democrats get more to center and become an alternative with more plans than to try cover all ethnicities with promise of handouts.