In my opinion, we have the most right-wing government we have had in my lifetime. Again, in my opinion, the far-right tends not to be too bothered with reality, does not do the admin, doesn't care about scientific findings, etc. A sweeping generalisation, I know. However, we have to live with the stereotyping in the right-wing client media, so I see no reason not to respond correspondingly. It seems to me (opinion) that the further to the right you go, the only people seen as living effectively are the rich. That cannot be right.
The hard left does the same. They form opinions and then make the facts fit. One of those "facts" we see affecting the thinking of the right is that the wealthy 'use' money better than either other people or governments. I think this is too extreme; the extreme it becomes unbelievable and should be continuously tested and not taken for granted.
So no, I am not convinced CGT sweepingly "serves a purpose in business". I am not even sure what exactly you might mean by that. I can see no reason why the profit made on the buying and selling of shares, where the person is not involved in any other way in the business, should not attract at least the same as the continuing tax someone would pay if they earned more by working.
I can see the need for those investing and working in small and medium-sized enterprises to have some return on their tax if profit is paid back into businesses but not if it is taken as a form of earnings or simply a dividend.
One person's wealth will always be another person's poverty. We must be extremely careful of the widening of the gap between them and continually ask ourselves why inequality is so high in the UK. In this country most of the rich get their initial wealth because it is left to them. I can see no reason why that wealth should be "better", and therefore treated more favourably, than earned income.