If you're worried about price and pricing Apple, you're doing it wrong. You could put the SSD in a Thunderbolt enclosure and it'll be just about as fast, if a little awkward to carry around and plug in often.
There are plenty of non-Apple but good manufacturers with flexibility. Hell, I don't like Dell for their price points, but all of the laptops I've seen from them have upgradeable RAM and storage. If you want even more customization there are things like Framework.
Well, I am worried about doubling the price of the laptop for 3.5TB. External SSDs are a significant extra and (technologically) completely unnecessary complexity and inconvenience.
> There are plenty of non-Apple but good manufacturers with flexibility.
There are plenty of non-Apple but good manufacturers with flexibility. Hell, I don't like Dell for their price points, but all of the laptops I've seen from them have upgradeable RAM and storage. If you want even more customization there are things like Framework.