I've been in the business of getting people to use ideologically-driven technology for most of my career (with one or two exceptions). Leaving out the less ideologically driven positions, it goes something like this:
Elgg: We needed to convince people that, if they're going to run an online community, they should use one that allows them to store their own data anywhere, embraces open standards, and can run in any web browser (which, at the height of Internet Explorer's reign, was a real consideration).
Latakoo: In a world where journalism is experiencing severe budget cuts, we needed to persuade newsrooms that they shouldn't buy technology with astronomically expensive licenses and then literally build it into the architecture of their buildings (when I first discovered that this was happening, it took a while for my jaw to return to the un-dropped position).
Known: We needed to convince people that, if they're going to run an online community-- oh, you get the idea.
Matter: We needed to convince investors that they should put their money into startups that were designed to have a positive social mission as well as perform well financially - and that media was a sound sector to put money into to begin with.
Unlock: We need to persuade people that they should sell their work online through an open platform with no middleman, rather than a traditional payment processor or gateway.
That's a lot of ice skating uphill!
So how do you go about selling these ideas?
One of the most common ideas I've heard from other startup founders is the idea of "educating the market". If people only knew how important web standards were, or if they only knew more about privacy, or about identity, they would absolutely jump on board this better solution we've made for them in droves. We know what's best for them; once they're smarter, they'll know what's best for them too - and it's us!
Needless to say, it rarely works.
The truth comes down to this: people have stuff to do. Everyone has their own motivations and needs, and they probably don't have time to think about the issues that you hold dear to your heart. Your needs - your worries about how technology is built and used, in thise case - are not their needs. And the only way to persuade people to use a product for it to meet their deeply-held, unmet needs.
If you have limited resources, you're probably not going to pull the market to you. But if you understand the space well and understand people well, you can make a strong hypothesis about whether the market is going to come to you at some point. If you think the market is going to want what you're building two or three years out, and you can demonstrate why this is the case (i.e., it's a hypothesis founded on research, not just a hunch) - then that's a good time to start working on a product.
Which is why, while many of us were crowing over the need for web products that don't spy on you for decades, it's taken the aftermath of the 2016 election for many people to come around. Most people aren't there yet, but the market is changing, and tech companies will change their policies to match. The era of tracking won't come to an end because of activist developers like me - it'll come to an end because we failed, and Facebook's ludicrous policies (which, to be clear, aren't really different to the policies of many tech companies) reached their damaging logical conclusion, allowing everyone to see the full implications.
So if an ideology-first approach usually fails, how did we persuade people?
The truth is, it wasn't about the ideology at all. Elgg worked because people needed to customize community spaces and we provided the only platform at the time that would let them. Latakoo worked because it allowed journalists to send video footage faster and more conveniently than any other solution. Known didn't work because we allowed the ideology to become its selling point, when we should have concentrated on allowing people to build cross-device, multi-media communities quickly and easily (the good news is that because it's open source, there's still time for it). Unlock will work if it's the easiest and most profitable way for people to make money from their work online.
You can (and should) build a tool ethically; unless you're building for a small, niche audience, you can't make ethics be the whole tool. Having deep knowledge of, and caring deeply about, the platform doesn't absolve you from the core things you need to do when you're building any product. Which, first and foremost, is this: make something that people want. Scratch their itch, not yours. Know exactly who you're building for. And make them the ultimate referee of what your product is.