⛏ Another solo miner mined a block and received a reward of 6.49 BTC  

Its power is only 750 TH. With this hashrate, the probability of getting a block is 1 time in 9 years at the current mining difficulty.

❔ Solo mining compared to connecting hardware to a pool is pure lottery. The chance of getting a block is very small, and most of these miners never receive a reward, but the lucky one immediately breaks the jackpot.