Hello hiramabiff and welcome to Pond Boss. As an answer to your questions:

1. No most of us here are not contractors. However Go big is getting advice from folks that have quite a bit of experience in building ponds. Eddie Walker is a contractor and built a beautiful pond of his own. Otto is a contractor considered one of the best pond builders known to man, read some of JoeG's threads and you'll realize he has plenty of experience building ponds, Chris Steelman also has plenty of experience building ponds as well.

2. Some folks like to do things themselves, sometimes for economic reasons, other times just because they have the time and some equipment and want to give it a try.

When folks ask for advice, then advice is given.

JHAP
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"My mind is a raging torrent, flooded with rivulets of thought cascading into a waterfall of creative alternatives."
...Hedley Lamarr (that's Hedley not Hedy)