There's actually a video I recorded today (but haven't yet edited or uploaded) that's about sticking with the long game, not the short game. As human beings, most of us are motivated by immediate results and instant gratification.
We get lucky once on a scratch card, and that immediately tells us that what we did was a good strategy and encourages us to play more. We approach that girl or guy we're interested in, and get rejected, and that one action and result puts us off doing it again.
In the short term, this seems fair enough, but take those two things and apply them to the long game:
Let's take the scratch card first, if you play once and win your first time, and then just keep playing and playing because of it, chances are you're going to lose quite a bit of money since the odds are stacked against you. The more times you repeat the experiment, the closer the results will get to their statistical probabilities, aka the more scratch cards you play, the closer you'll get to an overall loss or being down a bunch.
Now the case of approaching someone we like and getting rejected. The thing is, even if you have the social skill of a sleeping tree sloth and the looks of a baboon's a**, there are people out there who'll be interested in you for who you are - so even if your chances might have been low with a particular person, overall, out of the hundreds of people you'll like and could have potentially had a chance with - you have a pretty good shot with a high % of them. So if someone let that one rejection affect them, they'd be missing out.
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Same goes for YouTube. In the short run, you start off with a lack of supplies and ideas - or rather, you probably have supplies, and some ideas, but they might not end up being the thing that gets you any deal of success. So first you have that initial minor failure of realising you need to adapt and improve. Then you find growth is perhaps not as fast as you imagined, and you have to learn about SEO, advertising, monetisation, and a whole host of other things.. all the while you're perhaps only gaining a sub or two here and there.
If you're only in it for the short game, you'll just give up at that point, and leave because things started off slow, but just take a look at any of your favourite large YouTubers. Many of them did get lucky and grew faster than average even from the beginning, but many others had incredibly slow starts, with just 100-200 subscribers for their first couple of years or longer. Had they given up and only been in it for the short game, they'd never have the 100k+ or 1m+ subscribers they have today.
If you have a good strategy and good implementation, then you shouldn't care about whether your videos are having a good day or a bad day, just continue on, and as your amount of content increases, things will eventually balance in your favour over a larger number of results.