Building a transceiver from scratch is indeed great fun. Soldering the components on, winding the toroids, aligning the IF, setting up the filters. Then testing it all for smoke, and seeing if it works.
It's even better if you have designed the circuit, perhaps from Doug DeMaw's design guides.
Even putting on the knobs and connectors on the ready-built UBitX is fun too and can give some sense of achievement too.
It's all good.
Some areas of our hobby do however almost preclude home construction to some extent. Also as people get older they may find they don't have the dexterity or eyesight they used to have. We also have a huge chunk of the community who rarely turn on a soldering iron (that's if they own one). There are also people who travel for a living, or have little space, and having a ready-made transceiver makes more sense. We all may have a reason to purchase a commercially made transceiver.
This talk will give us some idea of whether they really are as good as the money you pay for them.
Trystan G0KAY