There is no ‘massive welfare bill’. There are three kinds of payments:
Virtuous, uncontroversial:** pensions, unemployment payments for short-term unemployed, carer’s allowance, illness benefit, maternity benefit**. One can quibble about the rates but no one seriously argues that this kind of redistribution should be abolished in a developed society.
Questionable, uncontroversial: child benefit. This is simply taxing everyone to give money back to everyone.
Questionable, controversial: income supports for very long-term unemployed, some disability payments, family income supplement, CES, BTEA This is where the issues are in the Irish system. You can stay on benefits for a very long time without facing financial sanction. Disability claimants have increased a lot in recent years, anecdotally it is easier to get medical approval than in the past. Family income supplement is nice but it helps employers keeps wages down. CES and BTEA sound lovely but there is zero evidence that they have done anything to help the employment prospects of their recipients on average.
Fraud inevitably exists, you read about people collecting their dead brother’s pension for years.
More commonly it’s probably possible to scam the system at the edges and for periods of time, but nothing systematic and for very long. The main cause of the welfare bill is the conditions of the schemes and the rates of payment.