Did this ever happen to you: You submit a feature request to the Product Owner for something you really felt was important to add to the product. Your feature request was unceremonially added to the backlog, never to be seen again. How do you deal with that?
When it happened to me, my initial reaction was finding the nearest corner, curling up in a ball and sobbing uncontrollably. Just kidding. But still, it hurts a bit when something you deem important is postponed by someone else. In my case, didn't expect the feature to be added to the next sprint. There's a roadmap and there are priorities that I can't oversee in my position, so no hard feelings. The point is: sometimes, your darlings are killed for you. That sucks.
I felt hurt in that situation. But you know what I did? I talked about it with a couple of people who felt the same way I did. Not in a stab-the-PO-in-the-back kind of way, but to share my frustration and to receive some reassuring words in return.
It's hard to stand up for what you believe is important on your own. You need people around you that share your vision and fight the same fight.
And guess what? This week, everybody in the company received an email requesting input on the roadmap for the coming year. The most popular ideas will be considered, weighed against business goals, and given a place on the roadmap. If it was just me trying to gain attention, my ideas might not have stood a chance. But it's not just me. There's a couple of my brothers in arms who put in the same feature request for the roadmap I did. So my ideas (and some of theirs, of course - I can't claim responsibility for all good ideas) have a bigger chance to end up on the roadmap, exactly because I choose to share them.
Preach your ideas like it's gospel. Validate your ideas on feedback of others so you know they're good ideas. Find people who feel the same. Get other people involved, for the pack is stronger than the lone wolf. You can't convince a group on your own. The only way for a single person to make everybody think different is one by one.