There are many online business coming and disappear over a period like matrix, revshare and the current trend is bitcoin & altcoins ICO projects. Imaging if btc or altcoins projects disappear over a period what would be the next preference to earn online. because very few people identified blockchain in the year 2009 and got some BTC now they are millionaire. similarly do we have any idea of what could be the next technology / business we can expect in future.
Bitcoin and altcoin will not destroyed in future so don't expect the other preference. Suppose it will drop in future some online marketing job is always opened in the world. We should try that one but Bitcoin is never end in the market because it is invented in 2009 still it will raise gradually in crypto market. So current scenario is bright and good this is enough for our satisfaction.