Write tests for your own new code; write tests for the legacy code you need to amend and keep being that never ending pain-in-the-ass noise about testing.
Some day, some of your services will roll out to production with some serious bug (then rolled back, fixed etc...). Seize that opportunity to write a unit-test for that very bug and gather your colleagues and let them see what little piece of code could have prevented. If they are not convinced, financial matters will be enough to convince management.
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Write tests for your own new code; write tests for the legacy code you need to amend and keep being that never ending pain-in-the-ass noise about testing.
Some day, some of your services will roll out to production with some serious bug (then rolled back, fixed etc...). Seize that opportunity to write a unit-test for that very bug and gather your colleagues and let them see what little piece of code could have prevented. If they are not convinced, financial matters will be enough to convince management.