i just want to add something to this point. part of the risk is not a matter of length of time, it is the matter of storing coins on exchanges. in other words when you are depositing your coins on an exchange even for a single second, as soon as that deposit is confirmed you are at risk of losing your money. the exchange can scam you that very instant.
which is why if you want to start trading, you should also consider this risk among other risks involving trading.
Exactly! At least, if I do research on exchange reputation and its current situation (deposits, especially withdrawals); then I have likely been safe in very short term. You are right that exchanges can turn into scam or can be hacked within seconds, no one knows.
Investigate first, have detailed plans to withdraw after buying coins on exchanges (preparation on wallets on your devices), and set up plans to withdraw, 5 minutes or longer.
BTW, I want to add one more point:
- After buying, it will be safer to withdraw small amount of coins to test withdrawal on that exchange for the coin you just bought.
- If small withdrawals get first confirmation, let's move all rest of your coins.