Thank you for sharing your experience, i think that's possible that you will earn more money by being only on cgtrader because like you have said many clients will take a look on both sites to compare the prices and since you will earn more here maybe it worth it, however they will be always some clients that they will buy the model even if it is a lot more expensive on turbosquid or even the opposite, because these clients can be big societies that will not care a lot about a few dollars of differences and they will buy the model directly when they found what they are looking for, or because they don't have time, some times a freelancer or an agency it is pressed by time and each second count so they will not lose time comparing prices here and there, if your model look great they will buy it whatever the price is.
Also the good thing in Turbosquid is that they show the certified "checkmate" models first and these models are expensive and this for some category of clients a good sign, it give the impression of high quality marketplace, they will feel that this marketplace is serious, unfortunately the low prices of many models in cgtrader that figure in the first pages and lines can give the impression of cheap and bad quality marketplace, it can be fishy for some people ! (like any other products they will be always some people that judge the product by its price and believe me it can make a difference) , also Turbosquid have changed recently their algorithms to show expensive models in first lines even if it is not checkmate and this can reinforce this image of serious and high quality marketplace.
By the way i wonder if you have any experience with other marketplaces apart from turbosquid and cgtrader ? something like sketchfab, 3docean, 3dexport...