If we are to cut the crap and face the facts, Bitcoin is at the top of cryptocurrencies simply because it has managed to attract the biggest amount of fiat (dollars, euro, etc) compared to other currencies (note that this has nothing to do with the so-called "market cap"). And it did so because it has been outpacing most other coins in terms of generating profits in the long term (while generating less losses when it didn't fare quite well, say in 2014-2015), apart from being the first mover, of course. Some coins have recently been (or had been in the past) more profitable than Bitcoin but they all lacked consistency, i.e. the capability of generating profits over long enough time frames. Conversely, if Bitcoin starts generating losses and that wouldn't be temporary while some other currency shows more profitability over the same time span, people will start losing interest in Bitcoin as a speculative asset and turn toward that currency. The inference is that if you want to make Bitcoin die a painful and miserable death, you should, first, make its prices at least stagnant, and, second, pour enough cash into some other coin (more or less decent in terms of technology behind it, say, Litecoin) while (and this is the most important point here) keeping this growth for a certain period of time until the process turns self-sustainable and self-reinforcing
That might not make a lot of sense in the past when Bitcoin was strong (since that would be outright prohibitively expensive), but things may change if, for example, Bitcoin fails to scale successfully. In fact, it may happen even without external and deliberate influence but just because of Bitcoin price declining for a sufficient amount of time on its own. And this is the point I want to discuss
In long term, obviously good suport economic so cannot drop in Bitcoin price.