$$\frac{2^{75.51747}}{8*10^9} = 6.759797398 * 10^{12} = 2^{42.62012}$$

So each person would have to generate approximately $$2^{42.6}$$ or 6.7 trillion keys for there to be a 0.1% chance of a Segwit address collision.

_So time to switch to taproot? hmm_

Filiprogrammer

 to calculate how many addresses would have to be generated for a collision:

 private keys that would have to be generated for there to be a 0.1% chance of a Segwit address collision.

bitcoin

[Bitcoin Puzzle] Probability of private key collisions, part 1

SimpleStacker

So if we adjust the reply from @shafemtol to calculate how many addresses would have to be generated for a collision:

$$N = 2^{160}$$
$$K \approx \sqrt{−2N*ln(0.999)} \approx 2^{75.5}$$

We get $$2^{75.5}$$ private keys that would have to be generated for there to be a 0.1% chance of a Segwit address collision.