Why might God give to those who do not rely on Him and depend on means (or worldly causes)?

Allah is the Sustainer, the Wise, the All-Knowing. He has guaranteed the sustenance of all His servants, believers and disbelievers alike. Trusting in Allah is one of the greatest means of sustenance. Allah may sustain those who do not trust in Him or do not believe in Him, according to His wisdom. This giving may be a test or a gradual enticement, as He states: ﴿So when they forgot that by which they had been reminded, We opened to them the doors of every [good] thing until, when they rejoiced in that which they were given, We seized them suddenly, and they were in despair.﴾ [Al-An'am: 44]. This world is not worth a mosquito's wing to Allah, so He gives it to those who do not deserve it. As for the Hereafter, He gives it only to those He loves.