I understand your point, and you aren't wrong, but you are short-sighted. You may only sell to big clients now, but you are also leaving a lot of money on the table for yourself, not your company, yourself.
You've been selling for 20 years? How many of your customers have you had for longer than 3?
Now I can hear your mind churning, 'but I'm at a different company now! I don't sell the same thing!'. It doesn't matter. Sales is sales. And the best sales people foster relationships for years before they really sell the big bucks. And can go back to those same clients and sell different products and it's easy because those clients know them and trust them.
Ever get that little pang of jealousy wondering why that guy you know in sales plays golf every day with clients and doesn't seem to do much else? It's not because he's just that good. He's not. He might even suck. It's most likely bc he has been building relationships with those clients for years and they would buy a cactus as a new pillow if he asked them to.
This attitude of telling the little guy to piss off bc he isn't your type of client might make for some ok sales now, maybe you even have a shiny BMW, but it doesn't make for long term relationships with people who trust you. Once those people at that big company move on to bigger and better things, you'll be stuck grinding it out with whoever they replace them with.
I take it you work hard. You're certainly passionate. But after 20 years in sales, you shouldn't have to be working hard. Whether you changed companies and products every six months or still work for the same company, you should have been building relationships.
Instead you are content writing off the little guy as a waste of your time. The same senior management you grind it out to sell to now who was a little guy 20 years ago. And the same little guys who will be senior management in 10 - 20 years.
I imagine you'll still be grinding it out every day then also, instead of playing golf like you should be.