But how is it corrupt? I think you're getting confused about what corruption is. Corruption can only occur with those who have power, who are typically not the ones who receive the benefits of welfare.
There are some issues where people can claim a lot of money in benefits and live on it, sure. But they're a tiny minority and as said before, we're likely to be heading in that general direction anyway.
It's also not that big of an issue in the grand scheme of things. In the UK, £172.3 billion was spent on all welfare in 2015/16 where an estimated £1.9 billion was fraudulent (1.1%). (
https://www.gov.uk/government/upload...-estimates.pdf). Compare this to £2.7 billion lost through tax avoidance and £4.4 billion through tax evasion (
https://fullfact.org/economy/tax-avoidance-evasion-uk/).
In short, it does a lot more good than it does bad.