This isn't true in my experience as a party operator at all. You can easily move MAGA to progressive quite simply, do some deep canvassing but you'll find out that there are more agreements that people care about (healthcare costs, housing costs, poor salaries, poor retirement, decaying society) where you can build on top of.
Also what you're saying goes against the most effective union advice from people like Jane McAlevey that have successfully implemented strikes with >95% participation rates and getting workers effectively everything they ask for. Want to know how she is able to achieve this? She talks to those that people respect and follow in the workplace, often these people are at odds against you.
In her books she has given example after example on how she would convert people that were leading the anti-union efforts into being pro-union joining the cause.
Sorry man, just because your organizational skills are terrible doesn't me that there aren't real effective ways to do this.
Those people weren't ideologically against you on housing, healthcare, or poor salaries etc. If they were, you wouldn't be able to convince them. The reason they were easier to move is because of their class position. If you talked to a business owner, they would be against improving many of those things, particularly poor salaries and retirement. Healthcare keeps employees tied to work too.
With workers, there isn't an economic interest against changing those positions. With a business owner there is. I'm sure you understand this since you are talking about unions. In the taxonomy I described, I would categorize the people you're talking to as "soft" or "uninformed" because you are encouraging them to take action in their own interest.
Once again, I implore you to actually do some political organizing because you're just spouting nothing meaningful in general. Good luck.