Your first, and probably 'biggest', the problem is that you choose a very competitive niche in "self-development", "self-help", "motivation" etc. This is the same space as some pretty big names such as Tony Robbins, Grant Cardone, Gary Vaynerchuk, etc. Even though Grant and Gary could be considered business and financial motivation and advice but when someone searches on those keywords there going to get self-help and motivation too because they are crossover niches.
But you do have a shot to achieve your goal but first is understanding that you're on an uphill path because of the highly competitive niche you're in. So my advice would be to get aggressive and start uploading good content and as much of it as you can do. All optimized with keywords, SEO, titles, descriptions and great thumbnails because in very competitive niches flooding, with equally good content, is your only chance of getting views and subs because there is soo much other good channels and content out there for them to watch, answer the question "Why Do They Need To See My Video's?"
You don't need subs. You need more views. And to get more views you need better content. Better content will get you more views, in time, and more views will get you more subs, eventually. It's that simple. If your views are low it means your content is not reaching enough ppl. Check your analytics. If you don't understand how to read your analytics watch some videos that will teach you how to read them.
Figure out what works on your videos and what doesn't work and adjust accordingly. Change what needs to be changed to improve your videos. Make sure you are using TubeBuddy's features to their fullest to help.
Ok, so here is the deal. This is the single most asked question not only on this forum... but in the entire world. I'm being dramatic of course, but the problem is that this gets asked so often that the people who have been around for a while are tired of giving the same answers over and over...
@Avocado, hate to disagree with on the $$$ side of it, but it's been proven by more than a few people on YouTube that you do not. Granted most of these videos, where they mention this, is AFTER they have made it. But that's only because no one really documents their journey on YouTube when just starting out because for one they don't know if it's going to last "or kick-off" or whatever. But I have changed that into categories. I have a Billionaire channel where I have made a bet with an ACTUAL billionaire (who's a friend of mine) that I can become a billionaire within 15 years. That's why my channel is "Billionaire2033" because the bet was made in the summer of 2018. Also, another channel where I document my journey of becoming a music producer from scratch.
Hopefully, these two channels will end up inspiring people in 2021 and change things around for some people who are going through hard times.
Yup, I have to agree with @CyberSorcerer as well. YouTube search is FAR more powerful and can put you in front of FAR more eyes than any paid promotion could. And it's free... you simply need to do your due diligence and research proper SEO techniques and strategies. And that does not account for the occasional bout of virality.