Unpopular Opinion: Remaining a F2P is (usually) stupid.
First, I realize money is not easy to come by for many people, and there are obstacles. However, if you live in America, are able-bodied, and plan on playing TF2 for more than 50 hours, remaining an F2P is, in the vast majority of cases, a dumb choice.
1) The F2P experience is objectively far worse: Beyond not being able to voice chat, or call for medic, the biggest issue is not being able to trade for different weapon unlocks. Your inventory spots are limited and it is just luck of the draw as to if a weapon you want drops. Some unlocks, such as crusader's cross bow, are simply required to play a class well or in your own preferred play style.
2) You are wasting your time if you like the game and are playing as an F2P. If you have a lot of hours in this game, or want to get good at it, just buy premium. It is objectively stupid to spend 50 hours of your life having far less fun, and progressing far more slowly because you are unwilling to spend $5.
3) $5 is not a lot of money If you are able bodied and live in America, there is no reason why you cannot earn/be gifted/beg for $5. Usually this will take you less than an hour of work. Shovel a drive way, pick up dog poop, sell something you have, win some bets. If you have a credit card, paypal, or visa gift card, you are now good to go. If you don't ask a parent/friend/weird uncle to use their credit card for $5 of steam wallet funds and give them the cash. Anyone who isn't unreasonable will do this for you. Is everyone in your life being unreasonable? Great, then save up $15/$20, walk to any store, and buy a steam gift card.
4) $5 gets you a ton in-game. Buy 2 keys and you can get every single weapon in the game, a full cosmetic loadout for every class, and, probably, a strange version of your favorite weapon. The best news? You can always sell these things for real money, or to buy different cosmetics and weapons.
My heart goes out to all you F2Ps and how hard your life has been made in this game. But if you like the game, is worth $5 to play the full game, plain and simple.
Edit: 52% upvote rate. This opinion is indeed unpopular
Edit 2: if your parents are so controlling they won't let you earn $5 that you decide what you do with , you have much bigger issues.