Your argument is that the philanthropy of the ruling class will fulfill the required redistribution of wealth?

So far it hasn't worked out too well...

Not quite. The argument is that our tech elites aren't so evil to try to violently take over and that us masses can simply vote a more (much more) socialist system.

It's up to us. Indeed easier said than done in the current dysfunctional and polarized politics of ours but we can still do it.

We have pretty different views on tech elites. I don't think they are evil per se, but most are greedy and generally lack empathy. It's almost impossible to go from mildly wealthy to multi-billionaire status without some aggressive wealth accumulation.

For the philanthropy, I'll just note that these pledges don't involve literally transferring 99% of wealth out of their control. The vast majority of the pledged money goes to a trust the person controls, organizations they have some relation to, or just stay completely in their control for years with only vague non-binding commitments to eventually donate it. In return for this largess they get significant reputational and tax compensation.