3. Customer information - You do not get the customer information, which means you cannot sell to them again. What business does not have customers? Amazon is only one channel, a big one, but you should have your own customers, or at least emails of prospective customers to work from.
4. Fees - Amazon does a lot of work to fill your products and they charge at least 20% of the product, more if you store products for a long time. There are constantly adding more fees (sometimes fees on fees!)
So while, you should use Amazon to sell your products, you should have your own off Amazon presence, that also creates sales, effectively another sales channel, to protect yourself from the changes at Amazon that you have little control over. You need your own customers and email lists to build you and your family's income security.
Here is the hard question, if you have a large amount of income coming from Amazon and that stopped tomorrow, would you have to find a job? and quickly.