I don't have any expensive lenses but then I don't do photography for a living either. I have looked at a lot of photo's taken with other than expensive lenses that are absolutely super! I'm not sure even a pro could really justify the cost of some of the high dollar lenses for no other reason than their client's will never know the difference! I shoot trial dogs casting off. I use a 55-300 Nikon lens, not the best but does a job that everybody seem's to like. For placement shots I use an 18-105 Nikon, more than good enough for what I do. I would like to have a good high dollar lens for no other reason than to say I have it! Here is a couple photo's of my Squirt I took with an old, film days, Sigma 70-300 lens. I don't think anyone would call this a high quality lens but then I think the photo's are more than alright. How much better would they have to be with an expensive lens to make the expensive lens worth buying?
Our Tamron rep here has taken and posted a lot of absolutely super photo's taken with after marker lenses that are not high dollar lenses. I think what you have to ask yourself is, how good is good?