I wondered if my DS2 would ever self settle. But he does now - most of the time. I found his babyhood much easier than DS1's where i listened to other people and not myself enough. I knew DS2 was not going to settle without me - so i never got so upset when things didn't go 'to plan'.
I don't think leaving him to cry or 'sleep training' would have made me more happy or him more happy. I think it's really important that you do what really makes you feel the most comfortable - because you have to live it. If you want to just let things go now - then do that. I don't believe that you are setting yourself up for years of unsettled nights.