I think you can start with small amount accordingly if you fail you don't lose much
But what happen if he's success ? Will he being regret because he only spent a little amount on this time. Human's greed is hard to being pleasured. 
if he's success then he can have bigger money so he can prepare to buy another coin and try to make another profit. every trader should know his limit and will determine how much amount he want to use for day trading. i realize that if we use small amount, we can not make big profit but we still have another time to make big profit so i think we don't have to regret. the only thing that we can do is trying to trade more and more so finally we can make big profit.
Day trading can be considered as an example of a greed. Why would one person who invest in some coins can't wait and need the profit on the same day ? This is why it is called day trading as you get profit or loss in the same day and since the trader tends to be greedy here, profit is day trading is very rare and only for big investors.