While its true some people just "collect" cards because they can and it can be addicting.
Somebody like me, however, started out after BK with NO credit cards, so I had to work my way up starting with the garbage cards, then no-frills cards, then the mid-level cards, and now I'm finally getting "respectable" cards. I organically grew my card portfollio that way, and now I'm in account contraction mode.
I have >20 cards... the majority of which I don't really need. My goals are to maximise my cashback, have at least one of each major card network, and to have a diverse portfolio of backing banks. So I want to have at least an MC, Visa, Amex and Discover. That's four cards. To have at least two issuing banks for the MC and Visa, that's at least another two cards. So my Overall Plan is to have at a minimum 6 cards to achieve my diversity goals. But I have to be careful how I contract, because I do not want to drop my available credit faster than my reporting balances. So, as I get CLI's on my preferred cards, non-preferred cards get closed.
Now that I just did an $8,000 0% balance transfer to pay off a Prosper loan, I ratcheted up my usage, so I'm on pause with closing accounts until I pay that off. The temprorary score hit is worth it for the $1,400 saved in interest over 18 months!
I hope that kind of helps with another perspective.
@CH-7-Mission-Accomplished wrote:You have stumbled on the site that is the AA of credit card junkies. If you were on a site for wine enthusiasts, you would wonder why people are willing to pay $1000 for a bottle of wine when they can get something decent for $30. How many baseball cards does a person need?
$30? That's Special Occasion wine prices! I pride myself on finding the $12-$20 bottles that are good for my regular wine consumption. 
I was given a glass from a $500 bottle of wine at an event once... I wasn't impressed. Another guest at the table with me was actually offended that I didn't like the wine. They kept going on about where the grapes came from and the history of the region and why that made it better than anything from Napa Valley or Door County or wherever. All I kept saying was "If it doesn't taste good, what good is the pedigree?"
That reminds me of some of the credit card bank snobbery that you occasionally see here... "You haven't succeeded in your rebuild until you have a Chase Saphire."
@CH-7-Mission-Accomplished wrote:You have stumbled on the site that is the AA of credit card junkies. If you were on a site for wine enthusiasts, you would wonder why people are willing to pay $1000 for a bottle of wine when they can get something decent for $30. How many baseball cards does a person need?
Good analogies but there's only one AA of credit thread here. 
I think everyone else pretty much hit all of the points. If your cards work for you, that is wonderful and there is zero need to apply for any more. Personally, I have a few reasons. Foremost is that while I'm paying off lots and lots of it, I have a lot of revolving debt that I've been carrying for about a decade, so I need the utilization padding. Next, I tend to primarily use one card and I have massive spend since basically everything but my mortgage, other loans and credit card payments get charged. Because of that, I've found myself being "maxed out" during a cycle before a payment is made - even with 5-digit credit lines. Finally, I like free stuff - I'm being rewarded with thousands and thousands of dollars in free travel for just making purchases that I would have been making anyway, so if there's say a $500 (or equivalent) signup bonus somewhere I'm probably going to take the issuer up on it.
@Dalmus wrote:That reminds me of some of the credit card bank snobbery that you occasionally see here... "You haven't succeeded in your rebuild until you have a Chase Saphire."
Oh come on, let's make it Amex Centurion, at least.
