I'm sorry but how old/young are you? This is not to put you down, but this helps to give some context to myself and others in your views.
Injection of money was never an issue. When Jack Walker first took over Blackburn Rovers back in 1991 and started breaking transfer records all over the place for the likes of Shearer and Sutton nobody talked about "financial fair play".
The reason for the emergence of FFP is largely due the implosion of
Leeds Utd. You might have remember them in the early 1990s as a solid top 6 club, and eventually being considered a force in EPL and Europe around late 1990s to early 2000s. What happened then was that they massively overspend, and took on massive loans against "future earnings" in prize money from European and EPL success. When the success didn't come, the club was heavily in debt and had to be put on administration, imposing strict wage restrictions and selling off almost all their players. (We got Rio out of this, luckily for us). It was so bad that "
Doing a Leeds" became a lexicon for football clubs financial mismanagement. They were not the only club, but were definitely the most famous case study. This lead to the emergence of some form of financial rules and restrictions to prevent a repeat.
Of course, subsequently a few clubs were bought by sugar daddies such as Chelsea by Abramovich and Fulham by Mohd Al-Fayed. They spent massively, distorting the transfer market and made it difficult for any other clubs outside of elite few to compete and sign players within financial means. Chelsea in particular also started hoarding players, not just top players but also potential future stars (because they can), and this led to serious concerns about the competitiveness of football, and that the game as a whole would be much worse off. Imagine, at one point of time they can afford to spend 7million (a huge sum back then) on a very young KdB and afford to not have him in the first or 2nd team. There was also concern that the rich owners might ditch the club one day and saddled the club with a lot of financial commitments in the form of transfer fee instalments, player salaries etc. that they couldn't reasonably pay without the owner's deep pocket, leading to another Leeds Utd.
And thus the FFP. On one hand, it certainly look like it's protecting the elite clubs, but these rules are also what made it possible for other clubs to sign good players (because no club can now hoard tons of players without breaking FFP), making it possible for the emergence of the likes of Brighton and the likes of Leicester City to win EPL.