Wash sales, a nightmare or bologna?

So let’s get down to everyone’s favorite questionable stock trading rule of wash sales. Some say you can keep trading and as long as you close your position by end of year it won’t really effect gains/losses. My standpoint here is if you are positive over the entire year “gains”.

So say I made a wash sale the other day for -$300. I want to keep trading that same stock/ETF without waiting the 30 days after. Theoretically if I were to trade again and make $10,000 dollars on same stock and close it by end of year, would I simply be taxed on the 10,000 or would it be 10,300?

Another example, if I lost $20,000 then made $10,000 would I pay taxes on $30,000? Thanks