How much Bitcoin is a “sat” (sats), as people often call it?
First, the definition: at the protocol level, Bitcoin amounts are actually recorded as whole numbers of sats; the decimals shown in wallets are just the converted amounts.
Why? Using sats to express small amounts is more intuitive: saying “1,000 sats” makes it easier not to miscount decimal places than saying “0.00001 BTC.”
$BTC You don’t have to buy a whole coin at once; fractions of a coin, or even smaller amounts, can also be traded. Currently 80434.01.
There’s no shame in taking it slow. Staying in the game matters much more than making a big profit on any one trade.

Just my personal opinion—don’t take it too seriously.