The odds, if looking at this realistically and taking measure of say the success expected from those 75,000 songs, is exceptionally small. Most musicians do it for the love of it, and the few who are bred/willed into becoming famous (think child prodigies or marketed kiddie pop bands) becoming the exceptions to the rule. It's easy to assume that of the 75,000 songs uploaded on any given day, none of the ones not backed in some way by a marketing campaign/record company will amount to anything ever. Maybe one indie artist a month on average sticks, gets used in a tik tok video, etc.
Browsing youtube for talent reveals that there's more talent on the planet than ears to listen to their musical output. There's a lot of people and as a percentage of the whole more musicians, but we still only need the same level of attention span lasting bands so there's not exactly an increase in the market overall. Meaning - we only need X number of bands to exist, because that's how many are needed to entertain people wanting to listen to music. It's not an infinite market.
I don't personally buy into the "hard work" thing, as that is a percent of a percent of a percent based on the same luck formula as someone who isn't good and doesn't work hard. Just make music for yourself, put it out there as you are willing (whatever level of effort that is for you), and appreciate the nominal success you're likely to achieve.