ANYTHING is possible with a big enough budget, enough time and focus, and energy. But taking that journey is EXTREME to say the least.
Could you start a new Twitter or a better Facebook today? Absolutely! Got millions to do so? A team of hundreds?
ONE person can get going but there will be a point where you hit such a massive wall that either you need the above (millions and a team) or you just stop and settle for whatever level you have reached.
But knowing this in advance helps make the decision easier. It all comes down to what you are willing to do (and not do).
Good luck. Oh, and LOL. :D