Gambling is merely betting or taking chance on the outcome which is uncertain. On the surface trading ODTE (0 day option expiring in same day as placing the contract) options is akin to gambling, but I beg to differ especially for the trader who is well informed and make calculated risks before placing the order. Let me elaborate.

Trading Options whether the expiry is ODTE or a couple of years, involves chance, where the outcome is based on probabilities, the outcome of which regardless of time expiry is beyond control. However one can choose carefully the underlying stock, the related data on the stock like its implied votality, the liquidity of the stock based on volumes traded and also if the stock is prone to be shorted.  All these data is readily available whether you place a ODTE or longer expiry options.  I think the most important decision is choosing the right stock using the right option strategy as every stock has its own personality.  For example you would not buy ODTE options on stocks that is less volatile as indicated by Its Beta usually less than 1 or super low volume stock that is less liquid as it is more difficult to exit. How can this be gambling especially if you have to exercise some form of analysis & also studying pre-market data and technicals as indicated by charts and the strengths of the stock based on financial fundamentals before entering any position. It is important to do your own due diligent & not follow the sentiments of the market. Some trader use the option strategy to buy stock at a discount (@HermanL). In this case he may place a ODTE sell put option ITM (in the money) & collect more premium as the stock will be likely assigned to him at his choice strike price.  His cost of purchasing the stock would then be the strike price less discount from the premium collected. 

In my opinion, buying shares based on sentiments of the market or your gut feel may tantamount to gambling compare to buying ODTE options who made a conscious decisions before trading.

However, In circumstances that you know the outcome is totally unpredictable like buying ODTE prior to release of financial data, this is likely akin to gambling as even for solid performing companies that meet targets the share price can go south after release of financial data, as eventually the post financial price is dictated by how the msrket interprete the data. ( I agreed with @JinHan). So I would not normally place ODTE on earnings release and other major events news release like the Fed decisions, etc as the outcome of the stock price is highly unpredictable, so you would be subjecting the outcomeof the contract purely based on chance-which then I think is like gambling.

So to conclude taking some form of risks is unavoidable, but trading after doing due diligence is taking calculated risks & not gambling. 

I wish goodluck to all in the Tiger community & hopefully we progress together.