My husband and I have a 16 year age gap (I'm the younger one). We met through mutual close friends drunk in a bar (everyone was drunk - no one can quite remember who introduced us - good times). Neither of us was out trolling for someone younger or older - it just happened. I'm financially independent and have a fairly well paying job - so it wasn't like I was out looking for someone older and financially stable. My husband is American - so it's not like he desperately needed Canadian PR. Again, it just happened.
When it comes to the 25+ year age gaps, I think it takes an exceptional couple and exceptional circumstances to really make that work.