The most popular advice you get if you're starting up is to have a singular focus on solving a primary user problem in order to have a chance of succeeding. If you are spreading your focus on multiple things, there is a good chance you will not get any of them to the level that will make a real difference. You may, at best end up being yet another product that fails to draw the customers' glances for more than a few seconds.
Yet, the moment you get start getting traction for your initial product, you soon start thinking about doing more. The very investors who wanted you to focus on one thing and do it well now want you to focus on a few additional things and do them well too. That is the key to attract more investors for further rounds of funding and attract more talent.
But it is not at all an easy call to take as to when to start doing more than what you started off doing. If you look at popular companies of different ages, the ones in the 1-3 years age group are all those that do one thing really well and nothing else (like Yo, Ello, Slack). The ones that are 8-10 years or older do several things well, although they aren't good at everything they do (like Google, Amazon, Facebook, Apple). The ones in-between are trying their hand at multiple things after having initial traction through one core product (like Ola).
To draw an analogy, I'll recount a personal story on when to take the decision to do more and how to go about it. At the start of the year, after a year and a half of near zero physical activity, I decided I want to complete a triathlon. I could have started to run, bike and swim all at once as I have to do all three in order to complete a triathlon. But I would have likely quit in a couple of weeks had I attempted that. So I decided to do the easiest (for me) of the three first. Run. For four months, I only focused on running until it turned into a habit, until I had a lot of time to think about what to do next and not worry about addressing any concerns around running. Then, I started biking along with running. For a month, the clock was turned back to four months previously. I had to do a lot of fire-fighting to just keep going with the new schedule. But slowly, I'm starting to overcome that phase and settle into the new routine. Only when I'm comfortable with this will I plunge into swimming.
The key here is excess. Excess of time and resources. Ultimately, whatever you do and how many ever things you do, you want to do them well. And you will only do them well when you're enjoying the act and you will only grow better when you have time (and resources) on your hand to think about how to shape your ship for the long haul and not be consumed with meeting the daily demands.
No investor is going to shower excess funds because excess needs to be earned and not handed over. If it is handed to you, 9 out of 10 times, you will just be a consumer and not show any returns on it. So, you have to earn it.
It is easiest to think up showcase newer products and make claims for them on your previously earned credibility. But unless you have the excess of time and resources to shape their journey, you are better off making your one thing better until you can afford to take your eyes off it for a bit to look at something else.