How is 0.3 BTC possible with alt trading without any investment? I don't think that's possible.
Who says it is possible in altcoin trading without investment? Ofcourse not, it is all about your capital in trading that decides if how much profit you will earn in a particular time, the bigger your capital is the more profit you will gain from your trade, no one can earn from trading without investment, even it is not possible to do trading without investment.
Also while basing on capital for your possible earnings, it must also be accompanied by a great wave of price fluctuations.
Without an active movement in price, without a rally, without a price trend or something like that, your profits is not active too. Trading gives profit not on regular basis that's why don't expect such fixed income every week if you relying on trading as method to earn bitcoin.