I think trading is the right place for earning 30usd to 100usd a day,but for expertise they can earn that maybe more than that,for me as a starter i will be honest with my working day to gain my honest pay day.
It would be enough to trade each day with 2% or 3% profit. (daytrading), but it is high risk.
Let us make a theoretical experiment.
• Go to Cryptopia or any other legit exchanger. The best, I think, is cryptopia for beginners.
• Deposit only 10$ (not more) in Bitcoin or altcoin.
• Study the cryptocurrencies
▪ Charts and historical data on coinmarketcap or blockfolio
▪ Read the coin info page on Cryptopia
▪ If you found interesting coins, look also here for infos
• Find out at least three coins, that are swinging since several weeks between certain price highs and downs.
• Buy and sell three different cryptocurrencies and go with the swings (the most difficult part, its like betting)
When you are able to gain profit of 3% each day, you will earn with your 10$
after month 1: 24,27$
after month 2: 58,92$
after month 3:143,00$
after month 4: 347,11$
after month 5: 842,53$
after month 6: 2.045,03$
after month 7: 4.963,83$
after month 8: 12.048,53$
after month 9: 29.244,94$
after month 10: 70.985,13$
after month 11: 172.299,55$
after month 12: 418.216,24$
For the case, you will not reach the target, blog your experiences on trading or write articles, when you have learned enough about cryptocurrencies and trading. Also trading journals are high visited.