Renting vs Owning Camera Lenses

"Shall I rent a lens or buy it?" "Are lens rentals worth it?" "Why would I rent a lens instead of buying it?"

These are three ways to express the same question, which seems to be in the mind of quite a few photographers (especially advanced amateurs; beginners don't consider it, while pros generally know what to do). In today's article I'll offer my views and opinion on this matter. To express things as simply as possible, I'll use the structure of review articles, with pros/cons, whom is it good for and whom it's not, elaborating on the matter along the way

So, the pros of renting a lens:

+ ability to use an expensive, specialized piece of equipment for a price you can afford
+ avoidance of constant stress regarding an expensive lens being stolen or malfunctioning (however, read more below)
+ quite often, you won't need to drag a heavy lens to location as a lens rental can deliver it straight there

And the minuses:

- it's still expensive. Renting the Nikkor AF-S 200mm f/2 isn't as expensive as buying it, but it's still around $250 for a week - plus any extra expenses for shipping, insurance, etc - for a lens you won't keep. You better really, really need it (and can justify the expenses)
- not stressing about a lens being stolen or malfunctioning also depends on the insurance policies of the lens rental. Make sure you're familiar with the small print and know who will have to cover any expenses if something happens
- Not owning a lens means you don't have sufficient time to become familiar with it. If you travel for 7 days to an exotic location, at least one of them will be wasted on you becoming familiar with the subtleties of the lens - especially if, as usually is the case, we're talking about some exotic tele the likes of which you've never used before.

Renting a lens is good for you if:

1. You really, really know what you're doing; you've used similar lenses before and know what to expect
2. You're traveling on a once-in-a-lifetime trip with the express purpose of taking photos and need the lens in question (cliché but good example: safari)
3. You're expecting to actually make some money with the photos, and you can justify the expenses (example: taking photos at a local concert or other occasion)

Renting a lens is not suitable for you if:

1. Deep down you're just an enthusiast. You'll enjoy yourself more (and probably take better photos) if you stick to more accessible lenses that you can own and use regularly. 
2. Conversely, you're expecting to use the lens a lot, making money from it in a regular basis. You might be a pro (semi- or full time) who plans to specialize on, say, wildlife. If you need to rent a lens all the time, perhaps owning it would be a better investment.
3. If you simply want to try it. I know this is a bit controversial, but think about it: if you're using a Nikon D3400 and a Nikkor 18-140 (or a D810 and a 24-120; it's not so much a matter of level), why trying a lens you don't need and can't afford? Going from the lenses above to something like a Nikkor AFS 400mm f/2.8 (don't click the link if you don't want to see how much it costs!) will blow your mind, yes, but for what purpose? To simply brag to your online friends, posing with photos of the lens instead of showing photos taken with it? Spending hundreds of dollars to take photos of your back yard or uncle Joe for a week with a lens you will never buy is beyond pointless.