To really purchase BTC and ETH is very easy, some wallet even allow you to purchase with your credit card and deposit directly to your bank account. But it's not that easy to Exchange your altcoins for fiat. Is it the fact that altcoins are scattered in exchanges and you have to register in different exchanges that support the altcoin you want to trade or the fact that sometimes the price changes really fast and if you sell high it might take some time before your order get filled. I really find it really stressful/frustrating after all we went through alot of stress while participating in airdrop/bounty.
Trading is not an easy job or task,especially you are a newbie into this kind of investment,you must been educate first yourself,and find or experience more ideas on how to become a successfull traders,otherwise crypto traders is a good kind of bussiness but you must always aware thats you should not goes into fraud or loosing your capital,because in this kind of crypto investment theres so many scam exchanges or opportunist people who wants taking for your weakness especially you are a beginner into this kind of digital currency investment system.