1. They are expensive, that is why people that store low amount of cryptocurrencies prefer to use online wallet. But storing coins worth more than 1000, hardware wallet is recommended.
2. They are not convenient to use like online wallets that you can easily access and trade.
3. A malware from hackers can erase the address code a donor is sending to while
sending high amount of bitcoin. The address will be replaced by the hacker's bitcoin address. This could happen to altcoin of high amount too depending on the malware.
4. The random number generator can be insecure and create a private key that can be known to hacker.
1. I disagree. It's either spending some money on HW wallet or risking losing all coins (which probably worth more than a HW wallet).
2. That depends on HW wallet and wallet (which used to connect with HW wallet) you use. Ledger HW wallet and Ledger Live is quite convenient, even though the feature is limited for power user.
3. Regular wallet also suffer from this problem, but you can verify the copied address and transaction detail to prevent sending your coin to hacker.
4. Also applies to regular wallet