i want to buy bitcoin but i am confused on binance.

sorry for dangerous english.

i need to buy 1 bitcoin however i'm confused on binance.

lets imagined i bought 1 btc usd worth of 20okay.

tomorrow its worth fell to 10okay but i nonetheless ought to have 1btc with 10okay worth and if worth goes to 40okay then i still ought to have 1 btc.

i simply need to buy bitcoin not trade on spot buying and selling. and why i'm speaking about spot trading bcz when i search on internet i.e the right way to buy btc on binance every one exhibits buy usdt then commerce any crypto in spot buying and selling.

so i'm confused what i do.