Re: Living in a capitalistic structure. . . . .
Regardless of whether the Gates' are fabulously wealthy or not, the point is valid if perhaps a little overstated. Across the globe there are very few examples where non-capitalist countries out-perform capitalist ones on standard of living and general quality of life. Of course the definition of "capitalist" here is fairly broad and includes the countries of Europe, for example, which in many cases include a good dose of socialism with their underlying capitalist structures.
I think much of this expression of the quality of capitalist life is a necessary addition to her main statement about tax inequality, put there mainly to avoid the wrath of the right-wing loonies in America who would otherwise jump down her throat and brand her a communist for ever daring to suggest that America's tax system should in some way be re-jigged to actually provide some real benefit to the poor, rather than just dropping more money in the pockets of the rich (Trump tax cuts??).
I would like to think (perhaps very optimistically) that this is a shot across the bow, a warning that perhaps the ultra-billionaires of the world are finally starting to realise that the pendulum needs to swing the other way. America is probably the worst in this regard (of anything bigger than a crackpot dictatorship like Brunei or half the Middle East), where wealth inequality is spiralling out of control.