How do you scale, if the intrest makes you oay so much more?

[Ori Holzman]

I'm extremely new to this, please forgive me for my lack of knowledge and for starting a (possibly unnecessary) new thread. When investing/purchasing, doesn't the interest require you to end up paying a lot more then its actually value? Sometimes even double what it's actually being sold for? So how can you actually make money off this? Again, apologies for my lack of knowledge. A detailed answer would be much appreciated?