The solution usually isn't "better people." It's engaging people on the same goals and making sure each of them knows how their part fits with the others. It's also recognizing when hard stuff is worth doing. Yeah you've got a module with 15 years of tech debt that you didn't create, and no-one on the team is confident in touching anymore. Unlike acne, it won't get better if you don't pick at it. Build out what that tech debt is costing the company and the risk it creates. Balance that against other goals, and find a plan that pays it down at the right time and the right speed.
How to do that? Genuine question.
If it is only technical debt that is hard to understand or maintain, but otherwise works, you're going to have a tougher time of building a case unless you build a second, better version and show the differences. But you could collect other opinions and present that.
Ultimately you have to convince them to spend the time (aka money) on it and do it without making things worse and that is easiest to do with metrics instead of opinions