the derailment is directing itself ;)

diversity of opinion is a given when there are several cooks/guests. i don't think much of making a customer believe in a perfect world - sometimes customers have to be given the choice that there will only be more necessary bugfixes if they don't change over.

an upgrade with big version jumps will be all the more expensive than many small upgrades.

So what are all those Mainframes and Cobol programs good for?
Can I switch these off?

^^ there are also different cobol versions. apart from that, cobol programs are now ported to java for expensive money or expensive cobol developers are brought out of retirement ...

On a more serious note: All Oracle DBs we see running here are Oracle 11.2 mostly on Centos 7 or 6.8 or AIX. The JVM is our smallest problem by far.

They just took that stuff and move it into some Microsoft Clouds, where it will rot forever -- as long as the P&L looks good. The hellish version of an eternal software heaven.

cobol programs are now ported to java

And you are sure, that would be Java17 Bytecode? :-D
(Sorry for trolling.)

trolling must be your main occupation, or is the desperation already so great?
i can only speak of my customers, who gratefully pay for every upgrade to keep the software up to date and maintainable. and i'm not talking about always using the latest, but the customers have already fled java8 for support and license reasons alone ;)