If you are a trader, the last thing you want is to be is holding a large amount of coin you only value as a means to acquire BTC or $.

If you are an investor and have researched a coin, and better yet, use it, then bag-holding is what you want to be doing. Though the term bag-holder is meant to refer to someone who got it wrong and is sitting on a useless asset, it is commonly misused on this forum as anyone who is sitting on a large stash of a particular coin. No one knows for certain what coins will succeed or fail, so bag-holder is premature in this sense.

It's just a different mind-set. Both are a lot of work and require a skill-set (to be successful), but some people are wired better for one approach over the other.

The major difference is that the bag-holder gets to acquire spending power by sitting on what the trader wants and the trader gets to acquire what is most valued without taking the initial risks of getting the future market wrong.

There are a few people like Risto (https://bitcointalk.org/index.php?action=profile;u=68520) who are good at both.