> This especially hit me recently when I was on vacation and I was still thinking about things I could do the app instead of enjoying my vacation.

Welcome to entrepreneurship. This is a good sign from my perspective. At some point you will figure out how to worry about and ideate for your app/business and still learn to enjoy vacations.

> Don’t get me wrong, I love working on DisplayBuddy and it's incredibly fulfilling to wake up to messages from my users about how useful the app is for them, but it often gets really tight with my job, and I live with this constant feeling that I could do more for DisplayBuddy than I’m currently doing.

You'll probably always have that feeling. I've built several successful businesses (service based, SaaS, marketplace). Still get that feeling on occasion. I sold my interest in one business because that feeling was too strong! It was like shedding a "job" which was tough but refreshing. For another SaaS, I reinvested profits in paying for dev work that I could have done myself. But saving my time was important. You have to just triage your time and revisit that share regularly. And accept that your time is all you have, and it is limited. Do not give up steady income though; I think it is best to move more time to your app biz as revenue grows. It will be harder to build a new business with the pressure and anxiety from giving up that income.

> What've I've lately realised is that building a business is hard, even harder when you have a full time job.

For my marketplace, to get it going, I had to spend a lot of nights and weekends doing nothing but programming as I had a good full time job. Friends and family and SO didn't understand it. My significant other thought I was wasting my time and was not really supportive. When it became successful they were then supportive LOL. It can be lonely but you need to push through. Most aren't willing to do what's needed to start and build a successful business.

> What've I've lately realised is that building a business is hard, even harder when you have a full time job. No matter how much influencers on TikTok and Instagram talk about starting a side hustle for “passive” income, to be honest there’s nothing passive about any income.

I had two truly passive income businesses (kept one). It can happen. Usually takes a few years of hard work though to get it to that place. And you'll probably have to hire with the profits to remove you from the equation and be truly passive.

Personally, I'd re-invest profits into acquisition and try to build a profitable campaign. And then invest a good chunk of income from the day job into scaling it. I wouldn't quit your day job to try and keep building new features.

If people are paying for it, can you scale it now?

I built a marketplace. Then we got to $1k/mo recurring. Then reinvested money into more acquisition. And it added $1k/mo recurring revenue almost every month like clockwork until it hit almost $40k/mo recurring. We delayed taking profits until we could turn it into a small business. If you want side income, it's fine to take profits early, but that's probably the extent of how big it will be.

Attempt to scale now and reinvest all earnings and use your steady income if needed to figure out an acquisition campaign that will provide ROI. It's unlikely that quitting your day job and continuing to build new feature will be the best use of your time and money, even though it feels like it might.