A scholar from the past said in the Hadith book of al Tirmidhi, the Sahaaba didn’t agree that leaving any act was disbelief apart from leaving the salaah. And in the books of jurisprudence they mention that the one who doesn’t pray has left Islam.
There are no excuses for leaving the prayer, not work, not sickness, not travelling, not even things like war. Allah has legislated something for every hardship which means it must be prayed on time.
Umar (ra) was on his deathbed after having been stabbed and he was unconscious. One of the Sahaaba came in and said the prayer the prayer, as it was prayer time! This awoke him from his unconsciousness and he said, the prayer! There is no portion in Islam for the one that has left the prayer!
And the evidences for this are too many to list. It doesn’t matter if a person is working to earn for his family, or gives charity in the millions or fasts every single day if he is not praying.
If you are struggling, pray just the obligatory prayers, on time.
Along with this, the person must pray on time, know how to pray, what breaks the prayer and anything linked to the prayer like wudoo and so on.
But as for leaving it totally, then this shows what a person thinks of Allah, the One who ordained the Prophet (saw) to ascend to Jannah and meet Him and then Decreed the prayer whereas everything else was revealed via Jibreel and sent down to earth including Hajj, fasting, zakaah and so on.