Some numbers for the US.
The richest 400 people owned a total of 4.5 Trillion USD in 2023 [0].
The US federal spending in 2022 was 6.3 T [1]. The CBO projects a federal budget deficit of $1.6 T for 2024. Beware this is only federal level, not including spending and debt of individual states.
Government budgets are mind boggling.
Even taking all the assets of the richest people in the world (meaning nationalizing most companies) would only temporarily make a noticeable dent in government spending. Taxing them will make no difference. For most other countries these taxes will be even less relevant.
[0] https://www.forbes.com/sites/chasewithorn/2023/10/03/the-202...
[1] https://en.wikipedia.org/wiki/United_States_federal_budget