No, they are not necessarily unsuccessful in life. The number of peadophiles who do not act upon their fantasies is very hard to determine, but it's supposed to be larger than the anticipated 5% of the general population. For peadophiles who do act upon their fantasies, they are generally fathers, step-fathers, uncles, or brothers, friends of the family. Being fathers and step-fathers, sexual success is assumed and for the other categories there is no reason to suggest that they are unsuccessful in their social relationships or social standing.
The only group which is generally more composed of losers is that which acts upon fantasies and kills. These are obviously more widely reported in the news. Traditionally, killers in general are rather less sophisticated than Hannibal Lecter, and have low IQs, poor social skills, limited job prospects. There are a few exceptions to this, but generally it is the case.