EA maintains mere game time can get FIFA players content they want but the most recent proof that this doesn't work was provided by a player who figured out it takes literal years to get an FUT dream team.
FIFA is one of those rare games that still rely on peddling loot boxes in order to get obscene amounts of money but it sadly still works. Therefore, it's not really a surprise when EA makes ridiculous claims such as this approach being ethical or that it's possible to substitute payments with game time.
A disillusioned FIFA 21 player and streamer, going by ScudzTV on Twitter, made a thread where he calculated the amount of time or money it would take to put together his dream team.
Scudz's dream team would cost him 100 million coins, which would translate to play 66,666 matches at least. This translates to about 916 days of gameplay, which is just under three years of playing every hour of every day. It would obviously take longer for a human being since FIFA alone does not sustain human life but even with this absolute minimum, the option is not feasible since there is a new FIFA game every year and the player base moves on.
Another option the streamer examined was EA's suggestion to monitor the market. In order to get 100 million coins, it would take him every single hour of 69 days to trade, assuming he could pull of juicy trades with 10,000 coins profit on every one of them. If one were to turn this into a full-time job of eight hours per day, it would translate to just trading for 207 days. It would mean leaving the player only a few months to actually enjoy the game, after almost seven months of it being a literal job with no days off.
The last, but certainly not the least option is to outright buy the team. If Scudz managed 100,000 coins of profit for each 12,000 FIFA points spent, it would mean he had to buy the 12K pack 1,000 times. This translates to £79,990 / ~$111,000. It hardly warrants any further breakdown.