Let's say that I bought 2 million USD of goods(that's about about 4,283,572.49 BTC), wouldn't people notice this kind amount of money sent from one wallet to another? Also isn't there an IP address attached to each wallet? If these kinds of transactions are not common then it would be very noticeable if such amounts were to go back and forth.
What if in the possible future people send each other 100 million USD worth of BTCs?
If that day when 100m USD worth of BTC is sent regularly, each BTC would've been worth like $10,000 each to sustain this kind of transfers. Hence, the actual bitcoins sent would be smaller (approx. 10,000 coins for this transfer).
There is no IP address attached to each wallet. A relaying IP is broadcasted with each transaction when you send coins, but it is not your IP. It's a relay node, where thousands of transactions use this IP per day depending on the node's size.
If you buy 2m USD worth of goods now, people would notice this transaction but not know who it is from and to, especially when the sender and receiver do not reuse the addresses involved. (which is the norm anyway)
edit: and you'll drive up the prices if you do buy 20m worth of goods now. Probably like pushing the prices to the $30-100 range so you'll need to send less after all of this.
