I believe he does owe us because without loyal followers who have bought the albums, bought the concert tickets, read every article, listen to every interview and stick to his career like a limpet to a rock, he would be nothing.
You are talking about "get life" fans. MK sell many more albums then only to these fans. MK sell many concert tickets, but I am sure most people who buy are not "get life" fan. These casual fan are many, but don't think about what to deserve or not. MK don't "need" "get life" fans. Come on.
Mark built up a fanbase on music based on his unique sound with DS.
MK was lucky (DS music fresh in disco time) and BIA and MFN big hit much thank you from new CD product. Yes, DS and Ed B. work very hard to market DS music and sell albums, but it is business, not charity or "love". They sell product - you like it? Buy it. It cost X dollar. If MK had only little success, he would do like David Knopfler: keep to make music but on small scale.