I would say historically I had a lot of low $XXX sales for domains that today I might not even renew. A fair portion of domain sales even high $XXX and occasionally low $XXXX were to investors. Now investors are only paying low $XXX and less frequently as they have more TLD options. Newbies have loaded up on new TLDs whereas in the past they might have bought some lower-priced aftermarket domains. So the new TLDs have siphoned off a lot of domainer to domainer sales and some end user sales as well. Think about what 16 million new TLDs some premium translates into just in renewals - probably more than $200 million yearly that could have gone into .COM, .Net, .etc purchases. SEDO used to report median .COM sales of about $600 on its platform. So now that we are approaching two and a half years after new TLDs were launched, we know that many millions went into premium-priced new TLDs, so there have been hundreds of millions of dollars of resources expended on new TLDs which otherwise would have gone into legacy extensions.
Note that even before new TLDs were launched, average portfolio turnover was very low 1-2%.