There are many differences between Bitcoin and other coins in the market. All other coins in the market are directly dependent on Bitcoin. That is, if you observe the market of other coins in the market, on the contrary, if you observe the market of Bitcoin, then you will definitely see the difference. When the value of Bitcoin fluctuates slightly, the value of all other coins in the market fluctuates. Again it happens that there are some coins that will dump in line with the Bitcoin market but when Bitcoin is pumping again those coins are not pumping.
I partially will disagree on this not all are dependent, some are independent as well. The term likely to be used is "Bitcoin correlation". Bitcoin is said to be highly correlated to as many cryptocurrencies, mostly the top ones but we can not generalize it to all. There are some cryptocurrencies whose price movement is not affected at all by the fluctuation of Bitcoin prices. Price movements on this cryptocurrencies are dependent on so many other factors including the potentials of the coin and what it was created to serve, since they are not decentralized as Bitcoin, partnership can also play massive role when dealing with the price fluctuations.
With bitcoin as well rest of the altcoins every dip is an opportunity to make an investment. Very few make use of this while majority of the users just keep hold of the assets for the bull trend. To make a good profit out of bitcoin it is a must to move along with the market than just holding focusing on targeted growth.
Bitcoin is the forerunner of all cryptocurrency exchanges, which we can see that the whole world has seen the rise of cryptocurrency through Bitcoin. Simply put, Bitcoin reigns supreme when it comes to cryptocurrency discussions.
Based on the market performance we can say that investing in Bitcoin is a safe option, but the growth of Altcoins is fast and phenomenal. Besides Bitcoin we can dip other Altcoins because there are many Altcoins which have increased by almost 1000% in 4 months. With such gains comes risk although Altcoin dips will be riskier than Bitcoin dips.
From the details on your post, it's an advise for investors to choose other cryptocurrencies over Bitcoin because of how much profits can be made coincidentally, this should not be misleading as this thread may not be able to conduce such a suggestion. When we talk about this form of investment, Bitcoin supersedes not just on how long but also potentials, trust for adoption and longevity which is a big threat for many new cryptocurrencies as they quickly fade out the market, giving their investor loses.