This was a staggering sum. Having an affair is a poor way to find love. Samson was looking for love and found a female Judas who betrayed him. Samson was smart. So WHY did he succumb to Delilah.
All humans have temptations.
We increase our vulnerability by feeding the temptation by what we read and watch. Samson kept hanging around Delilah. Sin is more like a sliding board than a sudden cliff. Eventually we get going so fast we cannot stop. The initial decision often determines the outcome.