Macklemore concerts didn't kill 100 million people at minimum.
Include deaths due to poverty and lack of affordable healthcare under capitalism, overworking and dangerous working conditions, and all wars and counter-insurgency waged on alternative economic systems globally.
A lot of the language, for example "interest" comes from cattle culture. If you think about it, a cow produces other cows, so it bears interest. You can eat the cow (consume capital) or let the cow produce a stream of milk. Ownership of cows gave you great power.
So asking "the number of people killed by capitalism" is like asking "how many people were killed by everything that's not communism", which is pretty inane, since the point of communism is that it is an ideology, and mass killing for an ideology (that's not religion) is a part of the modern world, not the traditional world of cows and capital. The first ideological genocide was the slaughter of the Vendee peasants by the French revolutionaries, but it was merely the first of many times that urban ideologues slaughtered rural farmers.
[0] https://www.investors.com/politics/commentary/denmark-tells-...
[1] https://en.wikipedia.org/wiki/Excess_mortality_under_Joseph_...
[2] https://en.wikipedia.org/wiki/Khmer_Rouge
[3] https://historyincharts.com/chinese-death-totals-great-leap-...
And if you think "well, it doesn't have to go to the government", who else will take it? Who would buy something that they would have to sell 5% of each year? The government, being the only thing that wouldn't be affected by a wealth tax, would become the de facto buyer.
They all turned into paranoid dictators who did everything they could to stay in power, except for Mao who got lied to by other party leaders and regretted it in his final years. None of them represent what socialism really is. Tankies who worship them are a small minority.
Someone says they're going to make everything equal and they just need enough power to do it. Trouble is, that requires all the power, and a) the halfwits who end up in power are nowhere near as good as the people doing the work and taking the risks at deciding what to do and how to do it and b) the people who want all the power can just say that and the credulous believe them.