That COULD be 1 day, 1 year, 10 years, or never, mate.
If you were to use just a modicum of intelligence you'd think about it.
If a computer comes with a faulty component built in, or added, then you'd need it replaced as soon as you got it.
Dependent on what you're actually going to be using your computer for, you MAY need to upgrade components as and when the need arises. i.e. if you are a games player, with the rapid development of more realistic games AND their requirements, you MAY need to upgade your video/graphics card if there's a particular game that you wish to run. (You MAY also need to upgrade the storage capacity of your computer for larger games ... some already take several Gigabytes of room up, and this is VERY LIKELY to expand to the extent that even more games will be needing more room. i.e. larger hard disk drives.) The same could be true of video editing, audio editing, etc.
More powerful programs/applications require faster processors and/or RAM (Random Access Memory) ... the memory in your computer. This means that you MAY need to purchase a faster CPU or more RAM to run specific programs/applications. Be aware that specific motherboards are only able to run specific CPUs up to a certain rate. i.e. you MAY also need to purchase a new motherboard into which you would fit a new CPU. The same is true of RAM modules, too. i.e. you can't run DDR4 RAM on a DDR3 RAM motherboard.
If none of the above applies to you, you MAY be able to run a computer for many years without the need to upgrade anything.