Eggs and Baskets
The ROI attracted a lot of big IT companies into the country with grants and tax breaks and the like. All this contributed to the Celtic Tiger. The problem with this sort of strategy is that it's artificial and will only last as long as some other country offers a better deal. Add to that a global recession/downturn/slowdown* and you could end up with a mass exodus of employers.
If you have based a major part of your economic strategy on attracting one type of employer you could well be in trouble.
*Delete as applicable to your politcal allegience.