Don't know if I can ask this in here, but how secure is Avalanche network? How easy is it to attack POS?

To compromise the safety of the network they would need to control 70% of the amount currently staked. (so they would need to buy over 150 million AVAX (worth over $2 billion, but obviously a) if someone tried to buy that amount then it would push the price up a lot and so would cost far more than that and b) they wouldn't be able to buy all from stake that was locked and so have to buy from what's available in circulating and then stake it, increasing the amount required further to obtain 70%